U.S. patent application number 14/449415 was filed with the patent office on 2015-07-23 for positive type resist composition for use in liquid immersion exposure and a method of forming the pattern using the same.
The applicant listed for this patent is FUJIFILM Corporation. Invention is credited to Haruki INABE, Hiromi KOBAYASHI.
Application Number | 20150205205 14/449415 |
Document ID | / |
Family ID | 35207883 |
Filed Date | 2015-07-23 |
United States Patent
Application |
20150205205 |
Kind Code |
A1 |
KOBAYASHI; Hiromi ; et
al. |
July 23, 2015 |
POSITIVE TYPE RESIST COMPOSITION FOR USE IN LIQUID IMMERSION
EXPOSURE AND A METHOD OF FORMING THE PATTERN USING THE SAME
Abstract
A positive type resist composition for use in liquid immersion
exposure comprises: (A) a resin having a monocyclic or polycyclic
cycloaliphatic hydrocarbon structure, the resin increasing its
solubility in an alkali developer by an action of acid; (B) a
compound generating acid upon irradiation with one of an actinic
ray and a radiation; (C) an alkali soluble compound having an alkyl
group of 5 or more carbon atoms; and (D) a solvent.
Inventors: |
KOBAYASHI; Hiromi;
(Shizuoka, JP) ; INABE; Haruki; (Shizuoka,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
FUJIFILM Corporation |
Tokyo |
|
JP |
|
|
Family ID: |
35207883 |
Appl. No.: |
14/449415 |
Filed: |
August 1, 2014 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
13782148 |
Mar 1, 2013 |
8828643 |
|
|
14449415 |
|
|
|
|
13228135 |
Sep 8, 2011 |
8426109 |
|
|
13782148 |
|
|
|
|
12325472 |
Dec 1, 2008 |
8039197 |
|
|
13228135 |
|
|
|
|
11175366 |
Jul 7, 2005 |
7531287 |
|
|
12325472 |
|
|
|
|
Current U.S.
Class: |
430/270.1 ;
430/322 |
Current CPC
Class: |
C08F 220/22 20130101;
G03F 7/2041 20130101; C08F 220/26 20130101; Y10S 430/146 20130101;
G03F 7/0397 20130101; G03F 7/322 20130101; G03F 7/0392 20130101;
C08F 214/18 20130101; G03F 7/0046 20130101; G03F 7/0045 20130101;
G03F 7/0395 20130101; H01L 21/0274 20130101; Y10S 430/106 20130101;
Y10S 430/114 20130101; C07C 69/54 20130101; G03F 7/039
20130101 |
International
Class: |
G03F 7/039 20060101
G03F007/039; G03F 7/20 20060101 G03F007/20 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 7, 2004 |
JP |
2004-200679 |
Claims
1. A resist composition for ArF exposure, comprising; (A) a resin
having a monocyclic or polycyclic cycloaliphatic hydrocarbon
structure, the resin increasing its solubility in an alkali
developer by an action of acid; (B) a compound generating acid upon
irradiation with one of an actinic ray and a radiation; (C) a resin
containing an alkyl group having 2 or more carbon atoms; and (D) a
solvent; and wherein the structure of resin (A) and the structure
of resin (C) are not in the same compound.
2. The resist composition for ArF exposure according to claim 1,
wherein a content of the resin (C) is 1 to 10 mass % on the basis
of the total solid content of the resist composition.
3. The resist composition for ArF exposure according to claim 2,
wherein the resin (C) contains an unsubstituted alkyl group having
2 to 20 carbon atoms.
4. The resist composition for ArF exposure according to claim 3,
wherein the resin (C) contains a repeating unit derived from a
(meth)acrylic acid derivative having an unsubstituted alkyl group
having 2 to 20 carbon atoms.
5. The resist composition for ArF exposure according to claim 4,
wherein the resin (A) contains a lactone group.
6. The resist composition for ArF exposure according to claim 5,
wherein the resin (A) contains no aromatic group.
7. The resist composition for ArF exposure according to claim 1,
wherein the resin (C) contains an alkyl group having 5 or more
carbon atoms.
8. The resist composition for ArF exposure according to claim 7,
wherein the resin (C) contains a fluorinated alkyl group having 5
or more carbon atoms.
9. The resist composition for ArF exposure according to claim 7,
wherein the resin (C) contains an alkali soluble group.
10. The resist composition for ArF exposure according to claim 9,
wherein the resin (C) contains a carboxyl group as the alkali
soluble group.
11. The resist composition for ArF exposure according to claim 9,
wherein the resin (C) contains a fluorinated alcohol as the alkali
soluble group.
12. The resist composition for ArF exposure according to claim 7,
wherein the resin (C) contains a group which is solubilized by
hydrolyzation with an alkali developer.
13. The resist composition for ArF exposure according to claim 12,
wherein the resin (C) contains a lactone group as the group which
is solubilized by hydrolyzation with an alkali developer.
14. The resist composition for ArF exposure according to claim 12,
wherein the resin (C) contains an ester group as the group which is
solubilized by hydrolyzation with an alkali developer.
15. The resist composition for ArF exposure according to claim 12,
wherein the resin (C) contains a sulfone amide group as the group
which is solubilized by hydrolyzation with an alkali developer.
16. A resist film formed by using the resist composition for ArF
exposure according to claim 1.
17. A pattern forming method, comprising exposing the resist film
according to claim 16 with an ArF excimer laser.
18. The pattern forming method according to claim 17, wherein the
exposing is an immersion exposure.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This is a Continuation application of U.S. application Ser.
No. 13/782,148 filed Mar. 1, 2013, which is a Continuation of U.S.
application Ser. No. 13/228,135 filed Sep. 8, 2011, now U.S. Pat.
No. 8,426,109, which is a Continuation of U.S. application Ser. No.
12/325,472 filed Dec. 1, 2008, now U.S. Pat. No. 8,039,197, which
is a Continuation of application Ser. No. 11/175,366 filed Jul. 7,
2005, now U.S. Pat. No. 7,531,287, which claims priority under 35
U.S.C. .sctn.119 from JP 2004-200679, filed Jul. 7, 2004, the
disclosures of all of the above applications are incorporated
herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention concerns a positive type resist
composition for use in the step of manufacturing a semiconductors
such as IC, and lithographic steps for the manufacture of circuit
substrates, for example, in liquid crystals and thermal heads and
other photo applications, as well as a method of forming a pattern
using the same. Particularly, it relates to a positive type resist
composition suitable to exposure by a liquid immersion type
projection exposure systems using far UV-light at a wavelength of
300 nm or less as a light source, as well as a method of forming
the pattern using the same.
[0004] 2. Description of the Related Art
[0005] Along with refinement of semiconductor devices, development
has been conducted for making the wavelength of a exposure light
source shorter and making the numerical aperture of a projection
lens higher (high NA), and a developing apparatus having NA of 0.84
using, as a light source, an ArF excimer laser having a wavelength
at 193 nm has been developed at present. The resolution and the
focal depth can be represented by the following equations.
(Resolution)=k.sub.i(.lamda./NA)
(Focal depth)=.+-.k.sub.2.lamda./NA.sup.2,
where .lamda. is wavelength of an exposure light source, NA is a
numeral aperture of a projection lens, and k.sub.1 and k.sub.2 are
coefficients related to a process.
[0006] An exposure apparatus using an F.sub.2 excimer laser having
a wavelength at 157 nm as a light source has now under
investigation for attaining higher resolution by making the
wavelength further shorter but since the lens material used for the
exposure apparatus and the material used for the resist are
extremely restricted for shorting the wavelength, reduction of the
manufacturing cost for the apparatus and the material and for
stabilization of quality are extremely difficult, which have
resulted in the possibility that exposure apparatus and resist
having sufficient performance and stability can not be in time for
the requested term.
[0007] As a technique for improving the resolution of an optical
microscope, a so-called liquid immersion method has been known so
far of filling a liquid of high refractive index (hereinafter also
referred to as "liquid immersion solution") between a projection
lens and a specimen.
[0008] For the "effect of liquid immersion", the resolution and the
focal depth described above can be represented by the following
equations in a case of liquid immersion assuming the wavelength of
exposure light in air as .lamda..sub.0, the reflective index of the
liquid immersion solution to air as n, a conversing semi-angle of a
light as .theta., and NA.sub.0=sin .theta.:
(Resolution)=k.sub.1(.lamda..sub.0/n)/NA.sub.0
(Focal depth)=.+-.k.sub.2(.lamda..sub.0/n)/NA.sub.0.sup.2
[0009] That is, the effect of the liquid immersion is equivalent
with that in the case of using 1/n exposure wavelength. In other
words, the focal depth can be increased to n times by liquid
immersion in a case of a projection optical system of identical
NA.
[0010] This is effective to all sorts of pattern shapes and,
further, can be combined with super resolution technique such as a
phase shift method, a modified illumination method, etc. which have
been under investigation at present.
[0011] Examples of apparatus applying the effects described above
to the transfer of fine patterns of semiconductor devices are
described in JP-A No. 57-153433, JP-A No. 7-220990, etc., but they
do not described resists suitable to the liquid immersion
technique.
[0012] JP-A No. 10-303114 points out that control for the
refractive index of the liquid immersion solution is important
since the change of the refractive index of the liquid immersion
solution causes degradation of projected images due to spherical
aberration of exposure apparatus and discloses control of the
temperature coefficient of the refractive index of the liquid
immersion solution to a certain range, and water with addition of
additives for lowering the surface tension or increasing the
surface activity as a suitable liquid immersion solution. However,
disclosure of the additives or the resist suitable to the liquid
immersion exposure technique is not discussed.
[0013] Development of the recent liquid immersion exposure
technique is reported, for example, in Bulletin of the
International Society for Optical Engineering (Proc. SPIE), 2002,
Vol. 4688, p 11, and J. Vac. Sci. Tecnol. B, 17 (1999), etc. In a
case of using an ArF excimer laser as a light source, it is
considered that pure water (refractive index at 193 nm of 1.44) is
considered most prospective as a liquid immersion solution with a
view point of handling safety, and transmittance and refractive
index at 193 nm.
[0014] In a case of using an F.sub.2 excimer laser as a light
source, while a solution containing fluorine has been considered in
view of the balance between the transmittance and the refractive
index at 157 nm, no satisfactory solution in view of the
circumstantial safety and the refractive index has yet been found.
In view of the degree of the effect of liquid immersion and the
degree of completion of the resist, it is considered that the
liquid immersion exposure technique will be adopted at first to the
ArF exposure apparatus.
[0015] Since the resist for use in a KrF excimer laser (248 nm), an
image forming method of chemical amplification is used as a method
of forming resist images in order to compensate the lowering of
sensitivity caused by light absorption. Referring to the example of
the image forming method of the positive type chemical
amplification, this is an image forming method of decomposing an
acid generator in an exposed area by exposure to generate an acid,
converting the alkali insoluble group into an alkali soluble group
by Post Exposure Bake (PEB) using the generated acid as a reaction
catalyst and removing the exposed area by alkali development.
[0016] In the liquid immersion exposure, a resist film is exposed
through a photomask in a state where a space between the resist
film and the optical lens is filled with the dipping solution (also
referred to as a liquid immersion solution) to transfer the pattern
of the photomask to the resist film. However, it is anticipated
that the dipping solution permeates inside the resist film thereby
giving undesired effect on the performance of the resist.
[0017] When a chemical amplification resist is applied to the
liquid immersion exposure technique, the acid on the resist surface
generated during exposure is transferred to the liquid immersion
solution to change the concentration of the acid at the surface of
the exposed area. It is considered that this is extremely similar
with acid deactivation on the surface of the exposure area caused
by basic contamination of an extremely small amount at several ppb
level from the circumstance during Post Exposure time Delay (PED)
which caused a significant problem in the initial stage of the
development of the chemical amplification type positive resist but
the effect and the mechanism given by the liquid immersion exposure
on the resistor have not yet been apparent.
[0018] On the other hand, in a case of applying chemical
amplification type resist having no problem in the lithography by
usual exposure to the pattern formation by the liquid immersion
exposure, it has been found problems that development defects and
development residues (scums) are formed, or leaching of the resist
to the liquid immersion solution occurs.
SUMMARY OF THE INVENTION
[0019] In view of the foregoing problems in the prior art, the
present invention intends to provide a positive type resist
composition suitable to liquid immersion exposure capable of
suppressing the formation of development defects and scums, with
preferably less leaching of resist ingredients to the liquid
immersion solution upon pattern formation by liquid immersion
exposure, as well as a method of forming a pattern using the
same.
[0020] The present invention provides a positive type resist
composition for use in liquid immersion exposure of the following
constitution, as well as a method of forming the pattern using the
same, by which the foregoing object of the invention can be
attained.
(1) A positive type resist composition for use in liquid immersion
exposure comprising: (A) a resin having a monocyclic or polycyclic
cycloaliphatic hydrocarbon structure, the resin increasing its
solubility in an alkali developer by an action of acid; (B) a
compound generating an acid upon irradiation with one of an actinic
ray and a radiation; (C) an alkali soluble compound having an alkyl
group of 5 or more carbon atoms; and (D) a solvent. (2) A positive
type resist composition for use in liquid immersion exposure as
described in (1) above, wherein the alkali soluble compound (C) has
at least one or more of fluorine atom. (3) A positive type resist
composition for use in liquid immersion exposure as described in
(2) above, wherein the alkyl group of the alkali soluble compound
(C) has at least one or more of fluorine atom. (4) A positive type
resist composition for use in liquid immersion exposure as
described in any one of (1) to (3) above, wherein the alkali
soluble compound (C) has an alcoholic hydroxyl group in which the
alcohol moiety is a fluorinated alcohol. (5) A positive type resist
composition for use in liquid immersion exposure as described in
any one of (1) to (4) above, wherein the alkali soluble compound
(C) has a carboxylic group. (6) A method of forming a pattern
comprising: forming a resist film by a resist composition as
described in any one of (1) to (5) above; subjecting the resist
film to liquid immersion exposure, so as to form a exposed resist
film; and developing the exposed resist film.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] FIG. 1 is a schematic view of an experimental apparatus for
two-beam interference exposure.
DETAILED DESCRIPTION OF THE INVENTION
[0022] The present invention is to be described specifically
below.
[0023] In the description for a group (atomic group) in the present
specification, description with no indication of "substituted or
not-substituted" includes those not having substituent and those
having substituent. For example, "alkyl group" includes not only an
alkyl group not having a substituent (not-substituted alkyl group)
but also an alkyl group having a substituent (substituted alkyl
group).
(A) Resin which is Decomposed by the Effect of an Acid and
Increases the Solubility in an Alkali Developer (Also Referred to
as an Acid Decomposable Resin(A))
[0024] A resin for use in a chemical amplification type resist
membrane for liquid immersion exposure according to the invention
is a resin having a monocyclic or polycyclic cycloaliphatic
hydrocarbon structure which is decomposed by the effect of an acid
and increases the solubility in an alkali developer (acid
decomposable resin), and having a group which is decomposed by the
effect of an acid to generate an alkali soluble group (hereinafter
also referred to as "an acid decomposable group" on the main chain
or the side chain of the resin or on both of the main chain and the
side chain. The resin of the invention can be preferably used, in
particular, for an ArF liquid immersion exposure.
[0025] The alkali soluble group includes, for example, a carboxyl
group, a hydroxyl group, and a sulfonic group.
[0026] a preferred group decomposable with an acid includes, for
example, a group in which a hydrogen atom of a --COOH group is
substituted with a group which is split with the acid.
[0027] The acid decomposable group preferably includes, for
example, a cumyl ester group, an enol ester group, an acetal ester
group and a tertiary alkyl ester group, with the tertiary alkyl
ester group being further preferred.
[0028] The resin contained in the positive type resist composition
for use in liquid immersion exposure of the invention is preferably
a resin having a group represented by the following general formula
(I) as the group which is decomposed by the effect of an acid to
generate an alkali soluble group (acid decomposable group):
##STR00001##
[0029] In the general formula (I),
[0030] R.sub.1 to R.sub.3 each independently represents an alkyl
group, a cycloalkyl group, or an alkenyl group. At least two of
R.sub.1 to R.sub.3 may bond with each other to form a ring.
[0031] As the alkyl group of R.sub.1 to R.sub.3, an alkyl group of
from 1 to 8 carbon atoms is preferred, and it includes, for
example, a methyl group, ethyl group, propyl group, n-butyl group,
sec-butyl group, 2-hexyl group, and octyl group.
[0032] The cycloalkyl group of R.sub.1 to R.sub.3 may be a
monocyclic or polycyclic, and specifically, it includes, groups
having a monocyclo, bicyclo, tricyclo or tetracyclo structure
having 5 or more carbon atoms. The number of carbon atoms is
preferably from 6 to 30 and particularly preferably, from 7 to 25
carbon atoms.
[0033] Preferred cycloalkyl groups of R.sub.1 to R.sub.3 are, for
example, an adamantly group, noradamantyl group, decalin residue,
tricyclodecanyl group, tetracyclododecanyl group, norbornyl group,
cedrol group, cyclohexyl group, cycloheptyl group, cyclooctyl
group, cyclodecanyl group, and cyclododecanyl group. More preferred
are an adamantyl group, noradamantyl group, decalin residue,
tricyclodecanyl group, tetracyclodecanyl group, norbornyl group,
cedrol group, cyclohexyl group, cycloheptyl group, cyclooctyl
group, cyclodecanyl group and cyclododecanyl group. A portion of a
hydrocarbon in the cycloalkyl group may be substituted with a
hetero atom such as an oxygen atom.
[0034] Preferred alkenyl group of R.sub.1 to R.sub.3, an alkenyl
group of from 2 to 8 carbon atoms and includes, for example, a
vinyl group, allyl group, butenyl group, and cyclohexenyl
group.
[0035] The alkyl group, cycloalkyl group and alkenyl group of
R.sub.1 to R.sub.3 may have a substituent. The substituent
includes, for example, an alkyl group, halogen atom, hydroxyl
group, alkoxy group, carboxyl group, alkoxycarbonyl group, cyano
group, and ester group. As the alkyl group, a lower alkyl group
such as a methyl group, ethyl group, propyl group, isopropyl group
and butyl group are preferred, and more preferably a methyl group,
ethyl group, propyl group and isopropyl group. The alkoxyl group
includes, for example, those having from 1 to 4 carbon atoms such
as a methoxy group, ethoxy group, propoxy group, and butoxy group.
The alkyl group and the alkoxy group may further have a
substituent. The substituent which may be present in the alkyl
group and the alkoxyl group includes, for example, a hydroxyl
group, halogen atom, and alkoxy group.
[0036] At least two of R.sub.1 to R.sub.3 may be bonded with each
other to form a ring, in which they may be bonded by way of a
hetero atom such as an oxygen atom.
[0037] The repetitive unit having the group represented by the
general formula (I) may be any repetitive unit, and a repetitive
unit represented by the following general formula (pA) is
preferred.
##STR00002##
[0038] In the general formula (pA), R represents a hydrogen atom, a
halogen atom or an alkyl group having from 1 to 4 carbon atoms.
Plural R may be identical with or different from each other.
[0039] A represents a group selected from a single bond, alkylene
group, ether group, thioether group, carbonyl group, ester group,
amide group, sulfoneamide group, urethane group and urea group,
alone or in combination of two or more of them. The alkylene group
may have a substituent.
[0040] R.sub.1 to R.sub.3 have the same meanings as those for
R.sub.1 to R.sub.3 defined in the general formula (I).
[0041] The repetitive unit represented by the general formula (pA)
is, most preferably, a repetitive unit derived from
2-alkyl-2-adamantyl(meth)acrylate or
dialkyl(1-adamantyl)methyl(meth)acrylate.
[0042] Specific examples of the repetitive unit represented by the
general formula (pA) is shown below.
(where Rx represents H, CH.sub.3 or CF.sub.3.)
##STR00003## ##STR00004## ##STR00005## ##STR00006## ##STR00007##
##STR00008##
[0043] In the acid decomposable resin (A), the content of the
repetitive group having the group represented by the general
formula (I) is preferably, from 10 to 60 mol %, more preferably,
from 1 to 50 mol % in the total repetitive units.
[0044] The acid decomposable resin (A) may have only the group
represented by the general formula (I) as the acid decomposable
group, or may have any other acid decomposable group in
combination.
[0045] The other acid decomposable group which may be present in
the decomposable resin (A) includes, for example,
--O--C(R.sub.36)(R.sub.37)(R.sub.38),
--O--C(R.sub.36)(R.sub.37)(OR.sub.39),
--O--C(.dbd.O)--O--C(R.sub.36)(R.sub.37)(R.sub.38),
--O--C(R.sub.01)(R.sub.02)(OR.sub.39),
--O--C(R.sub.01)(R.sub.02)--C(.dbd.O)--O--C(R.sub.36)(R.sub.37)(R.sub.38)-
.
[0046] In the formula, R.sub.36 to R.sub.39 each independently
represents an alkyl group, a cycloalkyl group, aryl group, aralkyl
group or alkenyl group. R.sub.36 and R.sub.37, and R.sub.38 and
R.sub.39 may be bonded with each other to form a ring.
[0047] R.sub.01 and R.sub.02 each independently represents a
hydrogen atom, an alkyl group, cycloalkyl group, aryl group,
aralkyl group or alkenyl group.
[0048] --C(R.sub.36)(R.sub.37)(R.sub.38) represents a group in
which each group represented by R.sub.36 to R.sub.38 is bonded to a
carbon atom by way of a single bond, here and hereinafter.
[0049] For the acid decomposable resin (A), the total amount of the
repetitive units having an acid decomposable group including a
repetitive unit having an acid decomposable group represented by
the general formula (I), as well as a repetitive unit having any
other acid decomposable group is preferably from 10 to 70 mol %,
more preferably, from 20 to 65 mol %, further more preferably from
25 to 50 mol % based on the total repetitive units.
[0050] The monocyclic or polycyclic cycloaliphatic hydrocarbon
structure contained in the acid decomposable resin (A) includes,
although not particularly restricted, a cycloalkyl group as R.sub.1
to R.sub.3 in the formula (I) described above and a cycloaliphatic
hydrocarbon structure present in the repetitive unit to be
described below.
[0051] The acid decomposable resin (A) preferably has at least one
unit, as the repetitive unit having a monocyclic or polycyclic
cycloaliphatic hydrocarbon structure, selected from the group
consisting of repetitive units having a partial structure
containing a cycloaliphatic hydrocarbon represented by the
following general formula (pI) to the general formula (pVI) and
repetitive units represented by the following general formula
(II-AB).
[0052] At first, the partial structure containing a cycloaliphatic
hydrocarbon represented by the general formula (pI) to the general
formula (pVI) is to be described.
##STR00009##
[0053] In the formula, R.sub.11 represents a methyl group, ethyl
group, n-propyl group, isopropyl group, n-butyl group, isobutyl
group or sec-butyl group, and Z represents an atomic group
necessary for forming a cycloaliphatic hydrocarbon group together
with a carbon atom.
[0054] R.sub.12 to R.sub.16 each independently represents a linear
or branched alkyl group of 1 to 4 carbon atoms or a cycloaliphatic
hydrocarbon group, providing that at least one of R.sub.12 to
R.sub.14, or either R.sub.15 or R.sub.16 represents a
cycloaliphatic group.
[0055] R.sub.17 to R.sub.21 each independently represents a
hydrogen atom, a linear or branched alkyl group of 1 to 4 carbon
atoms or a cycloaliphatic hydrocarbon group, providing that at
least one of R.sub.17 to R.sub.21 represents a cycloaliphatic
hydrocarbon group. Further, either R.sub.19 or R.sub.21 represents
a linear or branched alkyl group of 1 to 4 carbon atoms.
[0056] R.sub.22 to R.sub.25 each independently represents a
hydrogen atom or a linear or branched alkyl group of 1 to 4 carbon
atoms or a cycloaliphatic hydrocarbon group, providing that at
least one of R.sub.22 to R.sub.25 represents a cycloaliphatic
group. R.sub.22 and R.sub.24 may join with each other to form a
ring.
[0057] The cycloaliphatic hydrocarbon group for R.sub.11 to
R.sub.25 or the cycloaliphatic hydrocarbon group which is formed by
Z and carbon atoms may be monocyclic or polycyclic. Specifically,
it includes groups having a monocyclo, bicyclo, tricyclo, or
tetracyclo structure of 5 or more carbon atoms. The number of
carbon atoms thereof is preferably from 6 to 30 and, particularly
preferably, 7 to 25. The cycloaliphatic hydrocarbon groups may have
a substituent.
[0058] Preferred cycloaliphatic hydrocarbon group are an adamantly
group, noradamantyl group, decalin residue, tricyclodecanyl group,
tetracyclododecanyl group, norbornyl group, cedrol group,
cyclohexyl group, cycloheptyl group, cyclooctyl group, cyclodecanyl
group, and cyclododecanyl group. More preferred are the adamantly
group, decalin residue, norbornyl group, cedrol group, cyclohexyl
group, cycloheptyl group, cyclooctyl group, cylodecanyl group, and
cyclododecanyl group.
[0059] The substituent which may be present in the cycloaliphatic
hydrocarbon groups described above includes, for example, an alkyl
group, halogen atom, hydroxyl group, alkoxy group, carboxyl group,
and alkoxycarbonyl group. The alkyl group is preferably, lower
alkyl groups such as methyl group, ethyl group, propyl group,
isopropyl group, and butyl group and, more preferably, selected
from the group consisting of a methyl group, ethyl group, propyl
group and isopropyl group. The alkoxyl group includes, for example,
those having 1 to 4 carbon atoms such as a methoxy group, ethoxy
group, propoxy group, and butoxy group. The substituent which may
further be present in the alkyl group, alkoxy group and
alkoxycarbonyl group, includes, for example, a hydroxyl group,
halogen atom and alkoxy group.
[0060] The structure represented by the general formulae (pI) to
(pVI) in the resin can be used for the protection of the alkali
soluble group. The alkali soluble group include various groups
known in the relevant technical field.
[0061] Specifically, the alkali soluble group includes, for
example, a carboxylic acid group, sulfonic acid group, phenol group
and thiol group, and the carboxylic acid group and the sulfonic
acid group are preferred.
[0062] The alkali soluble group protected by the structure
represented by the general formulae (pI) to (pVI) in the resin
includes, preferably, a structure in which the hydrogen atom of the
carboxyl group is substituted with the structure represented by the
general formulae (pI) to (pVI).
[0063] Specific examples of the repetitive units having the
structure in which the hydrogen atom of the carboxyl group is
substituted with the structure represented by the general formulae
(pI) to (pVI) include, for example, those identical with the
specific examples of the repetitive units represented by the
general formula (pA).
[0064] It is more preferred that the resin of the ingredient (A)
contains the repetitive units having a group represented by the
general formula (1A).
##STR00010##
[0065] In the formula (IA),
[0066] R.sub.x represents a hydrogen atom or a methyl group.
[0067] R.sub.y represents an alkyl group of 1 to 6 carbon atoms.
The alkyl group of 1 to 6 carbon atoms in R.sub.y may be linear or
branched, and may be not substituted, or may have a further
substituent. The substituent which may be present in the alkyl
group is, for example, an alkoxy group of 1 to 4 carbon atoms,
halogen atom (fluorine atom, chlorine atom, bromine atom, or iodine
atom), acyl group, acyloxy group, cyano group, hydroxyl group,
carboxyl group, alkoxycarbonyl group, or nitro group.
[0068] The repetitive unit represented by the formula (IA) includes
repetitive units derived from 2-methyl-2-adamantyl(meth)acrylate,
2-ethyl-2-adamantyl(meth)acrylate,
2-propyl-2-adamantyl(meth)acrylate,
2-isopropyl-2-adamantyl(meth)acrylate,
2-butyl-2-adamantyl(meth)acrylate, and
2-(3-methoxypropyl)-2-adamantyl(meth)acrylate. Preferred are
repetitive units derived from 2-methyl-2-adamantyl(meth)acrylate or
2-ethyl-2-adamantyl(meth)acrylate.
[0069] Next, the repetitive units having a cycloaliphatic structure
represented by the general formula (II-AB) are to be described.
##STR00011##
[0070] In the formula (II-AB):
[0071] R.sub.11' and R.sub.12' each independently represents a
hydrogen atom, cyano group, halogen atom, or alkyl group.
[0072] Z' represents an atomic group containing two bonded carbon
atoms (C--C), and for forming a cycloaliphatic structure.
[0073] Furthermore, the repetitive unit represented by the general
formula (II-AB) is preferably repetitive units represented by the
following general formula (II-A) or the general formula (II-B).
##STR00012##
[0074] In the formulae (II-A) and (II-B):
[0075] R.sub.13' to R.sub.16' each independently represents a
hydrogen atom, halogen atom, hydroxyl group, cyano group, --COOH,
--COOR.sub.5, a group which is decomposed by the action of an acid,
--C(.dbd.O)--X-A'-R.sub.17', alkyl group or cyclic hydrocarbon
group, in which
[0076] R.sub.5 represents an alkyl group, a cyclic hydrocarbon
group or the following --Y group.
[0077] X represents an oxygen atom, sulfur atom, --NH--, or
--NHSO.sub.2-- or --NHSO.sub.2NH--.
[0078] A' represents a single bond or a bivalent bonding group.
[0079] Further, at least two members of R.sub.13' to R.sub.16' may
join to form a ring. n is 0 or 1.
[0080] R.sub.17' represents --COOH, --COOR.sub.5, --CN, hydroxyl
group, alkoxy group, --CO--NH--R.sub.6, --CO--NH--SO.sub.2--R.sub.6
or the following --Y group.
[0081] R.sub.6 represents an alkyl group or a cyclic hydrocarbon
group.
[0082] --Y group;
##STR00013##
[0083] in the --Y group, R.sub.21' to R.sub.30' each independently
represents a hydrogen atom or alkyl group. a and b each presents 1
or 2.
[0084] In the general formulae (pI) to (pVI), the alkyl group for
R.sub.12 to R.sub.25 is a linear or branched alkyl group having 1
to 4 carbon atoms. The alkyl group includes, for example, a methyl
group, ethyl group, n-propyl group, isopropyl group, n-butyl group,
isobutyl group, sec-butyl group, and t-butyl group.
[0085] Furthermore, the substituent which may be present in each of
the alkyl groups includes, for example, an alkoxy group of 1 to 4
carbon atoms, halogen atom (fluorine atom, chlorine atom, bromine
atom or iodine atom), acyl group, acyloxy group, cyano group,
hydroxyl group, carboxy group, alkoxycarbonyl, group and nitro
group.
[0086] In the general formula (II-AB), R.sub.11' and R.sub.12' each
independently represents a hydrogen atom, cyano group, halogen atom
or alkyl group.
[0087] Z' represents an atomic group containing two bonded carbon
atoms (C--C), and for forming a cycloaliphatic structure.
[0088] The halogen atom in the R.sub.11' and R.sub.12' includes,
for example, a chlorine atom, bromine atom, fluorine atom, and
iodine atom.
[0089] The alkyl group for the R.sub.11', R.sub.12', and R.sub.21'
to R.sub.30' is preferably a linear or branched alkyl group of 1 to
10 carbon atoms, more preferably, linear or branched alkyl group of
1 to 6 carbon atoms, and further preferably, a methyl group, ethyl
group, propyl group, isopropyl group, n-butyl group, isobutyl
group, sec-butyl group, and t-butyl group.
[0090] A further substituent in the alkyl group includes, for
example, a hydroxyl group, halogen atom, carboxyl group, alkoxy
group, acyl group, cyano group, and acyloxy group. The halogen atom
includes, for example, a chlorine atom, bromine atom, fluorine
atom, and iodine atom, the alkoxy group includes those having 1 to
4 carbon atoms, for example, a methoxy group, ethoxy group, propoxy
group and butoxy group, the acyl group includes, for example, a
formyl group and acetyl group, and the acyloxy group includes, for
example, an acetoxy group.
[0091] The atomic group for forming the cycloaliphatic structure of
Z' is an atomic group forming repetitive units of a cycloaliphatic
hydrocarbon which may also have a substituent and, among them, an
atomic group for forming a bridged cycloaliphatic structure forming
repetitive units of the bridged cycloaliphatic is preferred.
[0092] Skeletons of the cycloaliphatic hydrocarbon to be formed can
include those identical with the cycloaliphatic hydrocarbon group
for R.sub.11 to R.sub.25 in the general formulae (pI) to (pVI).
[0093] The skeleton of the cycloaliphatic hydrocarbon may have a
substituent. Such substituent includes R.sub.13' to R.sub.16' in
the general formula (II-A) or (II-B).
[0094] Among the repetitive units having the bridged cycloaliphatic
hydrocarbon, repetitive units represented by the general formula
(II-A) or (II-B) described above are more preferred.
[0095] In the repetitive units represented by the general formula
(II-AB), the acid decomposable group may be contained in the
--C(.dbd.O)--X-A'-R.sub.17', or may be contained as a substituent
present in the cycloaliphatic structure formed by Z'.
[0096] The structure of the acid decomposable group is represented
by --C(.dbd.O)--X.sub.1--R.sub.0.
[0097] In the formula, R.sub.0 represents a tertiary alkyl group
such as t-butyl group, or t-amyl group, 1-alkoxyethyl group such as
isobornyl group, 1-ethoxyethyl group, 1-butoxyethyl group,
1-isobutoxyethyl group, or 1-cyclohexyloxyethyl group, an
alkoxymethyl group such as 1-methoxymethyl group or 1-ethoxymethyl
group, 3-oxoalkyl group, tetrahydropyranyl group, tetrahydrofuranyl
group, trialkyl silyl ester group, 3-oxo cyclohexyl ester group,
2-methyl-2-adamantyl group, or mevalonic lactone residue. X.sub.1
is as defined for the X.
[0098] The halogen atom for the R.sub.13' to R.sub.16' is a
chlorine atom, bromine atom, fluorine atom or iodine atom.
[0099] The alkyl group for the R.sub.5, R.sub.6 and R.sub.13' to
R.sub.16' is preferably a linear or branched alkyl group of 1 to 10
carbon atoms, more preferably, linear or branched alkyl groups of 1
to 6 carbon atoms, and further preferably, methyl group, ethyl
group, propyl group, isopropyl group, n-butyl group, isobutyl
group, sec-butyl group, and t-butyl group.
[0100] The cyclic hydrocarbon group for R.sub.5, R.sub.6 and
R.sub.13 to R.sub.16' includes, for example, an alkyl group and
bridged hydrocarbon, and includes, for example, cyclopropyl group,
cyclopentyl group, cyclohexyl group, adamantly group,
2-methyl-2-adamantyl group, norbornyl group, bornyl group,
isobornyl group, tricyclodecanyl group, dicyclopentenyl group,
norbornane epoxy group, menthyl group, isomentyl group, neomentyl
group and tetracyclododecanyl group.
[0101] Among R.sub.13' to R.sub.16', a ring formed by bonding at
least two of them includes, for example, rings of 5 to 12 carbon
atoms such as cyclopentene, cyclohexene, cycloheptane and
cyclooctane.
[0102] The alkoxy group for R.sub.17' includes, for example, those
of 1 to 4 carbon atoms such as methoxy group, ethoxy group, propoxy
group and butoxy group.
[0103] An additional substituent for the alkyl group, cyclic
hydrocarbon group or alkoxy group includes, for example, hydroxyl
group, halogen atom, carboxyl group, alkoxy group, acyl group,
cyano group, acyloxy group, alkyl group or cyclic hydrocarbon
group. The halogen atom includes is chlorine atom, bromine atom,
fluorine atom, or iodine atom. The alkoxy group includes those of 1
to 4 carbon atoms such as methoxy group, ethoxy group, propoxy
group and butoxy group, and the acyl group includes, for example,
formyl group and acetyl group, and the acyloxy group includes, for
example, acetoxy group.
[0104] The alkyl group and cyclic hydrocarbon group includes those
described above.
[0105] The bivalent connection group for A' includes, for example,
a group selected from the group consisting of alkylene group, ether
group, thioether group, carbonyl group, ester group, amide group,
sulfoneamide group, urethane group and urea group, or a combination
of two or more of them.
[0106] Various kinds of substituents for R.sub.13' to R.sub.16' in
the general formula (II-A) or (II-B) may also be a substituent for
the atomic group for forming the cycloaliphatic structure or an
atomic group Z for forming a bridged cycloaliphatic structure.
[0107] Specific examples of the repetitive units represented by the
general formula (II-A) or (II-B) include the following units, but
the invention is not restricted to those specific examples.
##STR00014## ##STR00015## ##STR00016## ##STR00017##
##STR00018##
[0108] Among the acid decomposable resins (A), the content of
repetitive units having a partial structure including the
cycloaliphatic hydrocarbons represented by the general formulae
(pI) to (pVI) is preferably from 20 to 70 mol %, more preferably,
24 to 65 mol %, and, further, preferably 28 to 60 mol % in the
entire repetitive structural units.
[0109] In the acid decomposable resin (A), the content of the
repetitive units represented by the general formula (II-AB) is
preferably from 10 to 60 mol %, more preferably, from 15 to 55 mol
% and, further preferably, from 20 to 50 mol % in the entire
repetitive structural units.
[0110] In the acid decomposable resin (A) having the monocyclic or
polycyclic cycloaliphatic hydrocarbon structure, the acid
decomposable group represented by the general formula (I) and other
decomposing groups may be present in any of the repetitive units
having the partial structure containing the cycloaliphatic
hydrocarbon represented by the general formula (pI) to general
formula (pVI), repetitive units represented by the general formula
(II-AB), and repetitive units of other copolymerization ingredients
to be described later.
[0111] Further, the acid decomposable resin (A) preferably has a
lactone group and, more preferably, has repetitive units having a
group having a lactone structure represented by the following
general formula (Lc) or any one of the following general formulae
(III-1) to (III-5), in which the group having the lactone structure
may be bonded directly to the main chain.
##STR00019##
[0112] In the general formula (Lc), Ra.sub.1, Rb.sub.1, Rc.sub.1,
Rd.sub.1, and Re.sub.1 each represents hydrogen atom or alkyl
group. m and n each independently represents an integer of from 0
to 3, and m+n is 2 or more and 6 or less.
[0113] In the general formula (III-1) to (III-5), R.sub.1b to
R.sub.5b each independently represents hydrogen atom, alkyl group,
cycloalkyl group, alkoxy group, alkoxycarbonyl group,
alkylsulfonylimino group or alkenyl group. Two members of R.sub.1b
to R.sub.5b may join to form a ring.
[0114] The alkyl group for Ra.sub.1 to Re.sub.1 in the general
formula (Lc) and the alkyl group for the alkyl group, alkoxy group,
alkoxycarbonyl group or alkylsulfonylimino group for R.sub.1b to
R.sub.5b include linear or branched alkyl groups which may have a
substituent.
[0115] A preferred substituent includes, for example, alkoxy group
of 1 to 4 carbon atom, halogen atom (fluorine atom, chlorine atom,
bromine atom, or iodine atom), acyl group of 2 to 5 carbon atoms,
acyloxy group of 2 to 5 carbon atoms, cyano group, hydroxyl group,
carbonyl group, alkoxycarbonyl group of 2 to 5 carbon atoms, and
nitro group.
[0116] The repetitive unit containing a group having a lactone
structure represented by the general formula (Lc) or any one of the
general formulae (III-1) to (III-5) includes, for example, those in
which at least one of R.sub.13' to R.sub.16' in the general formula
(II-A) or the general formula (II-B) has a group represented by the
general formula (III-1) to (III-5) (for example, a group in which
R.sub.5 in --COOR.sub.5 is a group represented by the general
formula (Lc) or the general formulae (III-1) to (III-5)), or a
repetitive unit represented by the following general formula
(AI).
##STR00020##
[0117] In the general formula (AI), R.sub.b0 represents hydrogen
atom, halogen atom or alkyl group of 1 to 4 carbon atoms. A
preferred substituent which may be present in the alkyl group for
R.sub.b0 includes those previously exemplified as preferred
substituents which may be present in the alkyl group for R.sub.1b
in the general formulae (III-1) to (III-5).
[0118] The halogen atom for R.sub.b0 is fluorine atom, chlorine
atom, bromine atom, or bromine atom. R.sub.b0 is, preferably,
hydrogen atom.
[0119] A' represents single bond, ether bond, ester bond, carbonyl
group, alkylene group or bivalent group of the combination of
them.
[0120] B.sub.2 represents a group represented by the general
formula (Lc) or any one of the general formulae (III-1) to
(III-5).
[0121] Specific examples of the repetitive unit containing the
group having a lactone structure are to be described below, but the
invention is not restricted to them.
##STR00021## ##STR00022## ##STR00023## ##STR00024## ##STR00025##
##STR00026## ##STR00027##
[0122] The acid decomposable resin (A) may contain a repetitive
unit having a group represented by the following general formula
(IV).
##STR00028##
[0123] In the general formula (IV), R.sub.2c to R.sub.4c each
independently represents hydrogen atom or hydroxyl group, providing
that at least one of R.sub.2c to R.sub.4c represents hydroxyl
group.
[0124] The group represented by the general formula (IV) is
preferably, of a dihydroxy form or monohydroxy form, more
preferably, of a dihydroxy form.
[0125] The repetitive unit having a group represented by the
general formula (IV) includes, for example, those having a group in
which at least one of R.sub.13' to R.sub.16' in the general formula
(II-A) or (II-B) has a group represented by the general formula
(IV) (for example, R.sub.5 in --COOR.sub.5 is a group represented
by the general formula (IV)), or repetitive units represented by
the following general formula (AII).
##STR00029##
[0126] In the general formula (AII), R.sub.1c represents hydrogen
atom or methyl group.
[0127] R.sub.2c to R.sub.4c each independently represents hydrogen
atom or hydroxyl group, providing that at least one of R.sub.2c to
R.sub.4c represents hydroxyl group and preferably, two members of
R.sub.2c to R.sub.4c each represents hydroxyl group.
[0128] Specific examples of the repetitive unit having the
structure represented by the general formula (AII) are shown below,
but they are not limited to them.
##STR00030##
[0129] The acid decomposable resin (A) may have a repetitive unit
represented by the following general formula (V).
##STR00031##
[0130] In the general formula (V), Z.sub.2 represents --O-- or
--N(R.sub.41)--. R.sub.41 represents hydrogen atom, hydroxyl group,
alkyl group or --OSO.sub.2--R.sub.42. R.sub.42 represents alkyl
group, cycloalkyl group or camphor residue. The alkyl group,
cycloalkyl group, or camphor residue for R.sub.41 or R.sub.42 may
be substituted with halogen atom (preferably, fluorine atom).
[0131] The repetitive unit represented by the general formula (V)
includes those specific examples below, but they are not restricted
to them.
##STR00032##
[0132] The acid decomposable resin (A) can contain, in addition to
the repetitive structural units described above, various repetitive
structural units with an aim of controlling the dry etching
resistance, standard liquid developer adaptability, substrate
adhesion property, resist profile and, further, resolution, heat
resistance, sensitivity, etc. which are generally necessary
characteristics of the resist.
[0133] Such repetitive structural units include the repetitive
structural unit corresponding to the following monomers, but they
are not restricted to them.
[0134] This enables for fine control of the performance required
for the resin of the ingredient (A), especially,
(1) solubility to a coating solvent, (2) film-forming property
(glass transition point), (3) alkali developability, (4) film
reduction (selection of hydrophilic/phobic property, alkali
solubility group selection), (5) adhesion to substrate at not
exposed area, (6) dry etching resistance, etc.
[0135] Such monomers include compounds having one addition
polymerizable unsaturated bond selected, for example, from acrylate
esters, methacrylate esters, acrylamides, methacrylamides, allyl
compounds, vinyl ethers, and vinyl esters.
[0136] In addition, any of addition polymerizable compounds that
are copolymerizable with the monomer corresponding to the various
repetitive structural units described above also may be
copolymerized.
[0137] In the acid decomposable resin A, the molar ratio of each of
the repetitive structural units contained is properly set so as to
control the dry etching resistance or adaptability to standard
liquid developer, a substrate adhesion, profile of the resist and,
further, resolution, heat resistance, sensitivity, etc. which are
general necessary performances of the resist.
[0138] While the content of the repetitive structural units based
on the monomers of the further copolymerizable ingredients in the
resin can also be set appropriately depending on the desired
performances of the resist, generally, it is preferably 99 mol % or
less, more preferably, 90 mol % or less, further preferably, 80 mol
% or less based on the total mol number of the repetitive
structural units having a partial structure containing
cycloaliphatic hydrocarbon represented by the general formulae (pI)
to (pVI) and the repetitive units represented by the general
formula (II-AB).
[0139] The content especially of the repetitive units containing a
group having the lactone structure described above and the
repetitive units containing the group represented by the general
formula (IV) (hydroxyadamantane structure) is as follows.
[0140] Based on the summed total mol number of the repetitive
structural units having a partial structure containing the
cycloaliphatic hydrocarbon represented by the general formulae (pI)
to (pVI) and the repetitive units represented by the general
formula (II-AB),
[0141] the content of the repetitive units containing a group
having the lactone structure is preferably from 1 to 70 mol %, more
preferably, from 10 to 70 mol %, and
[0142] the content of the repetitive units containing the group
represented by the general formula (IV) is preferably, from 1 to 70
mol %, more preferably, from 1 to 50 mol %.
[0143] In a case where the composition of the invention is for
exposure to ArF, it is preferred that the resin has no aromatic
group in view of transparency to ArF light.
[0144] The acid decomposable resin (A) can be synthesized by
ordinary method (for example, radical polymerization).
[0145] For example, the general synthesis method comprises charging
monomer species into a reaction vessel collectively or in the
course of the reaction, dissolving them, for example, in ethers
such as tetrahydrofuran, 1,4-dioxane, and diisopropyl ether,
ketones such as methyl ethyl ketone, and methyl isobutyl ketone,
ester solvents such as ethyl acetate and further, in a solvent that
dissolves the composition of the invention such as propylene glycol
monomethyl ether acetate to be described later, making them
uniform, then optionally carrying out heating in an inert gas
atmosphere such as of nitrogen or argon and starting polymerization
by using a commercially available radical initiator (such as azo
type initiator, peroxides, etc.). If required, an initiator is add
or added divisionally and, after completing the reaction, the
reaction product is charged into a solvent and the desired polymer
is recovered by a method such as in the form of power or solid. The
concentration in the reaction is usually 20 mass % or more,
preferably, 30 mass % or more, further preferably, 40 mass % or
more. The temperature for the reaction is usually from 10.degree.
C. to 150.degree. C., preferably, from 30.degree. C. to 120.degree.
C., further preferably, from 50 to 100.degree. C.
[0146] The repetitive structural units may be used each alone, or
may be used as a combination of a plurality of them. In addition,
the resin may be used alone, or may be used as a combination of a
plurality of them.
[0147] The weight average molecular weight of the acid decomposable
resin (A), on the basis of polystyrene by a gas permeation
chromatography (GPC) method, is preferably from 1,000 to 200,000,
more preferably, from 3,000 to 20,000. By determining the weight
average molecular weight to 1,000 or more, heat resistance and dry
etching resistance can be improved, and by determining the weight
average molecular weight to 200,000 or less, the developing
property can be improved, and in addition, the viscosity is lowered
to result in improvement of the film-forming property.
[0148] Referring to the molecular weight distribution (Mw/Mn, also
referred to as dispersibility), those in a range usually, from 1 to
5, preferably, from 1 to 4, further preferably, from 1 to 3 are
used. The molecular weight distribution is preferably 5 or less in
view of the resolution, configuration of the resist, side wall of
the resist pattern and roughness.
[0149] The amount of residual monomers in the acid decomposable
monomer (A) is preferably, from 0 to 10 mass %, more preferably,
from 0 to 5 mass %.
[0150] In the positive type resist composition of the invention,
the blending amount of the acid decomposable resin (A) is,
preferably, from 40 to 99.99 mass %, more preferably, from 50 to
99.97 mass % based on the total solid content of the resist.
(B) Compound Generating Acid Upon Irradiation with One of an
Actinic Ray and a Radiation
[0151] The compound that generates acid upon irradiation with one
of an actinic ray and a radiation to be used for the positive type
resist composition for use in immersion exposure according to the
invention (hereinafter sometimes referred to as "acid generator")
is to be described below.
[0152] The acid generator used in the invention can be selected
from the compounds used generally as the acid generator.
[0153] That is, photoinitiator for photo-cationic polymerization,
photoinitiator for photo-radical polymerization, light
extinguishing agent for dyes, light discolorant, or known compounds
that generate acid upon irradiation with one of an actinic ray and
a radiation such as far UV-rays and X-rays used for microresist or
the like, as well as mixtures thereof can be properly selected and
used.
[0154] They include, for example, diazonium salt, phosphonium salt,
sulfonium salt, iodonium salt, imidosulfonate, oximesulfonate,
diazodisulfone, disulfone and o-nitrobenzylsulfonate.
[0155] For compounds in which the group or the compound generating
an acid upon irradiation with one of an actinic ray and a radiation
are introduced to the main chain or the side chains of the polymer,
for example, compounds described in U.S. Pat. No. 3,849,137, GP No.
3914407, JP-A Nos. 63-26653, 55-164824, 62-69263, 63-146038,
63-163452, 62-153853, and 63-146029 can be used.
[0156] In addition, compounds generating an acid by light described
in U.S. Pat. No. 3,779,778 and EP No. 126,712 can also be used.
[0157] Preferred compounds, among the acid generating agents,
include compounds represented by the following general formulae
(ZI), (ZII) and (ZIII).
##STR00033##
[0158] In the general formula (ZI), R.sub.201, R.sub.202 and
R.sub.203 each independently represents an organic group.
[0159] X.sup.- represents a non-nucleophilic anion.
[0160] The number of carbon atoms in the organic group as
R.sub.201, R.sub.202 or R.sub.203 is generally from 1 to 30,
preferably, from 1 to 20.
[0161] Two members of R.sub.201 to R.sub.203 may join to form a
ring structure, and the ring may have an oxygen atom, sulfur atom,
ester bond, amide bond, or carbonyl group therein.
[0162] As the group formed by joining two members of R.sub.201 to
R.sub.203 includes an alkylene group (for example, butylene group
or pentylene group).
[0163] Specific examples of the organic group as R.sub.201,
R.sub.202, and R.sub.203 include, for example, groups corresponding
to those in the compounds (Z1-1), (Z1-2), and (Z1-3) to be
described later.
[0164] Compounds having a plurality of structures represented by
the general formula (ZI) may also be adopted. For example,
compounds having such a structure that at least one of R.sub.201 to
R.sub.203 of the compounds represented by the general formula (ZI)
joins with at least one of R.sub.201 to R.sub.203 of other
compounds represented by the general formula (ZI).
[0165] Further preferred (ZI) ingredients include compounds (Z1-1),
(Z1-2), and (Z1-3) to be described below.
[0166] The compound (Z1-1) is an arylsulfonium compound in which at
least one of R.sub.201 to R.sub.203 of the general formula (ZI) is
an aryl group, that is, a compound having arylsulfonium as a
cation.
[0167] In the arylsulfonium compound, all of R.sub.201 to R.sub.203
may be an aryl group, and a portion of R.sub.201 to R.sub.203 may
be an aryl group, and the residues may be an aryl group and a
cycloalkyl group.
[0168] The arylsuofonium compound includes, for example,
triarylsulfonium compounds, diarylalkyl sulfonium compounds,
aryldialkyl sulfonium compounds, diarylcycloalkyl sulfonium
compounds, and aryldicycloalkyl sulfonium compounds.
[0169] The aryl group of the arylsulfonium compound is, preferably,
a phenyl group and a naphthyl group and more preferably, a phenyl
group. In a case where the arylsulfonium compound has two or more
aryl groups, the two or more aryl groups may be identical with or
different from each other.
[0170] The alkyl group which is optionally present in the
arylsulfonium compound is preferably a linear or branched alkyl
group of from 1 to 15 carbon atoms and includes, for example, a
methyl group, ethyl group, propyl group, n-butyl group, sec-butyl
group or t-butyl group.
[0171] The cycloalkyl group which is optionally present in the
arylsulfonium compound is, preferably, a cycloalkyl group of from 3
to 15 carbon atoms and includes, for example, a cyclopropyl group,
cyclobutyl group is cyclohexyl group.
[0172] The aryl group, alkyl group, or cycloalkyl group for
R.sub.201 to R.sub.203 may have an alkyl group (for example, of 1
to 15 carbon atoms), cycloalkyl group (for example, of 3 to 15
carbon atoms), aryl group (for example, of 6 to 14 carbon atoms),
alkoxy group (for example, 1 to 15 carbon atoms), halogen atom,
hydroxyl group or phenylthio group as a substituent. The
substituent includes, preferably, a linear or branched alkyl group
of 1 to 12 carbon atoms, cycloalkyl group of 3 to 12 carbon atoms,
alkoxy group of 1 to 12 carbon atom, and, most preferably, an alkyl
group of 1 to 4 carbon atoms, and alkoxy group of 1 to 4 carbon
atoms. The substituent may be substituted on any one of three
members of R.sub.201 to R.sub.203, and may be substituted on all of
the three members. In a case where R.sub.201 to R.sub.203 each
represents an aryl group, the substituent is preferably at the
p-position of the aryl group.
[0173] The non-nucleophilic anion as X.sup.- includes, for example,
a sulfonic acid anion, carboxylic acid anion, sulfonylimide anion,
bis(alkylsulfonyl)imide anion, and tris(alkylsulfonyl)methyl
anion.
[0174] The non-nucleophilic anion means an anion with extremely low
effect of causing nucleophilic reaction, which is an anion capable
of suppressing aging decomposition by intra-molecular nucleophilic
reaction.
[0175] The sulfonic acid anion includes, for example, an aliphatic
sulfonic acid anion, aromatic sulfonic acid anion, or camphor
sulfonic acid anion.
[0176] The carboxylic acid anion includes, for example, an
aliphatic carboxylic acid anion, aromatic carboxylic acid anion,
and aralkyl carboxylic acid anion.
[0177] The aliphatic group in the aliphatic sulfonic acid anion
includes, for example, an alkyl group of 1 to 3 carbon atoms,
specifically, a methyl group, ethyl group, propyl group, isopropyl
group, n-butyl group, isobutyl group, sec-butyl group, pentyl
group, neopentyl group, hexyl group, heptyl group, octyl group,
nonyl group, decyl group, undecyl group, dodecyl group, tridecyl
group, tetradecyl group, pentadecyl group, hexadecyl group,
heptadecyl group, octadecyl group, nonadecyl group, eicosyl group
and a cycloalkyl group of 3 from 30 carbon atoms, specifically, a
cyclopropyl group, cyclopentyl group, cyclohexyl group, adamantyl
group, norbornyl group, and boronyl group.
[0178] The aromatic group in the aromatic sulfonic acid anion
include, preferably, aryl group of 6 to 14 carbon atoms, for
example, a phenyl group, tolyl group, and naphthyl group.
[0179] The alkyl group, cycloalkyl group and aryl group in the
aliphatic sulfonic acid anion and aromatic sulfonic acid anion may
have a substituent.
[0180] Such substituent include, for example, a nitro group,
halogen atom (fluorine atom, chlorine atom, bromine atom, or iodine
atom), carboxyl group, hydroxyl group, amino group, cyano group,
alkoxy group (preferably of 1 to 5 carbon atoms), cycloalkyl group
(preferably of 3 to 15 carbon atoms), aryl group (preferably of 6
to 14 carbon atoms), alkoxycarbonyl group (preferably of 2 to 7
carbon atoms), acyl group (preferably of 2 to 12 carbon atoms),
alkoxycarbonyl oxy group (preferably of 2 to 7 carbon atoms), and
alkylthio group (preferably of 1 to 15 carbon atoms). The aryl
group and the ring structure which are present in each group may
further include alkyl group preferably of 1 to 15 carbon atoms as a
substituent.
[0181] The aliphatic group in the aliphatic carboxylic acid anion
includes those identical with the aliphatic group in the aliphatic
sulfonic acid anion.
[0182] The aromatic group in the aromatic carboxylic acid anion
includes those identical with the aromatic group in the aromatic
sulfonic acid anion.
[0183] The aralkyl group in the aralkyl carboxylic acid anion
includes preferably an aralkyl group of 6 to 12 carbon atoms, for
example, benzyl group, phenetyl group, naphthyl methyl group,
naphthyl ethyl group, and naphthyl methyl group.
[0184] The aliphatic group, aromatic group, and aralkyl group in
the aliphatic carboxylic acid anion, aromatic carboxylic acid
anion, and aralkyl carboxylic acid anion may have a substituent,
and the substituent includes, for example, a halogen atom, alkyl
group, cycloalkyl group, alkoxy group, and alkyl thio group, like
those for the aliphatic sulfonic acid anion.
[0185] The sulfonylimide anion includes, for example, a saccharin
anion.
[0186] The alkyl group in the bis(alkylsulfonyl)imide anion, and
tris(alkylsulfonyl)methyl anion is preferably an alkyl group of 1
to 5 carbon atoms and includes, for example, methyl group, ethyl
group, propyl group, isopropyl group, n-butyl group, isobutyl
group, sec-butyl group, pentyl group, and neopentyl group. Those
alkyl groups may have a substituent, and the substituent includes,
a halogen atom, and alkyl group, alkoxy group, and alkylthio group
substituted with a halogen atom, and the alkyl group substituted
with a fluorine atom is preferred.
[0187] Other non-nucleophilic anions include, for example,
phosphorous fluoride, boron fluoride, and antimony fluoride.
[0188] The non-nucleophilic anion for X.sup.- is preferably an
aliphatic sulfonic acid anion substituted at .alpha.-position of
sulfonic acid with a fluorine atom, an aromatic sulfonic acid anion
substituted with a fluorine atom or a group having a fluorine atom,
a bis(alkyl sulfonyl) imide anion in which the alkyl group is
substituted with a fluorine atom, and a tris(alkylsulfonyl)methide
anion in which the alkyl group is substituted with a fluorine atom.
The non-nucleophilic anion is, particularly preferably, a perfluoro
aliphatic sulfonic acid anion of 4 to 8 carbon atoms, and an
aromatic sulfonic anion having a fluorine atom and, more
preferably, nonafluorobutane sulfonic acid anion, perfluorooctane
sulfonic acid anion, pentafluorobenzene sulfonic acid anion, and
3,5-bis(trifluoromethyl)benzene sulfonic acid anion.
[0189] Then, the compound (Z1-2) is to be described.
[0190] The compound (Z1-2) is a compound in a case where R.sub.201
to R.sub.203 in the general formula (ZI) each independently
represents an organic group containing no aromatic ring. In this
case, the aromatic ring also includes aromatic rings containing
hetero atoms.
[0191] The organic group containing no aromatic ring as R.sub.201
to R.sub.203 has generally 1 to 30 carbon atoms, preferably, 1 to
20 carbon atoms.
[0192] R.sub.201 to R.sub.203 each independently represents,
preferably, an alkyl group, cycloalkyl group, allyl group, or vinyl
group, further preferably, a linear, branched, cyclic 2-oxoalkyl
group, or alkoxycarbonyl methyl group and, most preferably, the
linear or branched 2-oxoalkyl group.
[0193] The alkyl group as R.sub.201 to R.sub.203 may be either
linear or branched, and preferably includes a branched alkyl group
of 1 to 10 carbon atoms, for example, a methyl group, ethyl group,
propyl group, butyl group, or pentyl group. The alkyl group is,
more preferably, a 2-linear or branched oxoalkyl group, or
alkoxycarbonyl methyl group.
[0194] The cycloalkyl group as R.sub.201 to R.sub.203 is preferably
a cycloalkyl group of 3 to 10 carbon atoms and includes, for
example, a cyclopentyl group, cyclohexyl group, or norbornyl group.
The cycloalkyl group is, more preferably, 2-oxocycloalkyl
group.
[0195] The 2-oxoalkyl group may be any of linear, branched and
cyclic, and includes preferably, a group having >C.dbd.O at the
2-position of the alkyl group or cycloalkyl group.
[0196] The alkoxy group in the alkoxycarbonyl methyl group
preferably includes alkyl groups of 1 to 5 carbon atoms (methyl
group, ethyl group, propyl group, butyl group, and pentyl
group).
[0197] R.sub.201 to R.sub.203 may be substituted with a halogen
atom, alkoxy group (for example, of 1 to 5 carbon atoms), hydroxyl
group, cyano group or nitro group).
[0198] Two of R.sub.201 to R.sub.203 may join to form a ring
structure, and may have an oxygen atom, sulfur atom, ester bond,
amide bond, or carbonyl group in the ring. The group formed by
joining two member of R.sub.201 to R.sub.203 includes an alkylene
group (for example, butylenes group and pentylene group).
[0199] The compound (Z1-3) is a compound represented by the
following general formula (Z1-3), which is a compound having a
phenacyl sulfonium salt structure.
##STR00034##
[0200] R.sub.1c to R.sub.5c each independently represents a
hydrogen atom, alkyl group, cycloalkyl group, alkoxy group or
halogen atom.
[0201] R.sub.6c and R.sub.7c each represents a hydrogen atom, alkyl
group or cycloalkyl group.
[0202] R.sub.x and R.sub.y each independently represents an alkyl
group, cycloalkyl group, allyl group or vinyl group.
[0203] Any two or more of R.sub.1c to R.sub.5c, and R.sub.x and
R.sub.y may join to form a ring structure respectively, and the
ring structure may have an oxygen atom, sulfur atom, ester bond, or
amide bond.
[0204] Zc.sup.- represents a non-nucleophilic anion, and includes
those identical with the non-nucleophilic anion of X.sup.- in the
general formula (ZI).
[0205] The alkyl group as R.sub.1c and R.sub.5c is preferably a
linear or branched alkyl group of 1 to 20 carbon atoms, for
example, a methyl group, ethyl group, linear or branched propyl
group, linear or branched butyl group, or linear or branched pentyl
group.
[0206] The cycloalkyl group as R.sub.1c and R.sub.7c is preferably
a cycloalkyl group of 3 to 8 carbon atoms, for example, a
cyclopentyl group, or cyclohexyl group.
[0207] The alkoxy group as R.sub.1c and R.sub.7c may be any of
linear, branched or cyclic, and includes, for example, an alkoxy
group of 1 to 10 carbon atoms, and preferably, a linear or branched
alkoxy group of 1 to 5 carbon atoms (for example, methoxy group,
ethoxy group, linear or branched propoxy group, linear or branched
butoxy group, or linear or branched pentoxy group), a cyclic alkoxy
group of 3 to 8 carbon atoms (for example, cyclopentyloxy group,
and cyclohexyloxy group).
[0208] Preferably, any one of R.sub.1c and R.sub.5c is linear or
branched alkyl group, cycloalkyl group or linear, branched or
cyclic alkoxy group, and further preferably, the sum of the number
of carbon atoms in R.sub.1c to R.sub.5c is 2 to 15. This can
improve the solvent-solubility and suppress generation of particles
during storage.
[0209] The alkyl group and cycloalkyl group as R.sub.x and R.sub.y
are the same as the alkyl group and cycloalkyl group for R.sub.1c
to R.sub.7c, and 2-oxoalkyl group, 2-oxocycloalkyl group and
alkoxycarbonyl methyl group are more preferred.
[0210] The 2-oxoalkyl group and 2-oxocycloalkyl group include those
having >C.dbd.O at the 2-position of the alkyl group and
cycloalkyl group as R.sub.1c to R.sub.7c.
[0211] The alkoxy group in the alkoxycarbonyl methyl group includes
those identical with alkoxy groups as R.sub.1c to R.sub.5c.
[0212] The group formed by joining R.sub.x and R.sub.y includes a
butylenes group, pentylene group, etc.
[0213] R.sub.x and R.sub.y each represents, preferably, an alkyl
group of 4 or more carbon atoms, more preferably, an alkyl group of
6 or more carbon atoms, further preferably, an alkyl group of 8 or
more carbon atoms.
[0214] In the general formulae (ZII) and (ZIII), R.sub.204 to
R.sub.207 each independently represents an aryl group, alkyl group,
or cycloalkyl group.
[0215] The aryl group as R.sub.204 to R.sub.207 includes,
preferably, a phenyl group and naphthyl group, further preferably,
a phenyl group.
[0216] The alkyl group as R.sub.204 to R.sub.207 includes,
preferably, linear or branched alkyl group of 1 to 10 carbon atoms,
for example, a methyl group, ethyl group, propyl group, butyl
group, and pentyl group.
[0217] The cycloalkyl group as R.sub.204 to R.sub.207 includes
cycloalkyl groups of 3 to 10 carbon atoms, for example, cyclopentyl
group, cyclohexyl group, and norbornyl group.
[0218] The substituent which can be present in R.sub.204 to
R.sub.207 includes, for example, alkyl groups (of, for example, 1
to 15 carbon atoms), cycloalkyl groups (of, for example, 3 to 15
carbon atoms), aryl groups (of, for example, 6 to 15 carbon atoms),
alkoxy groups (of, for example, 1 to 15 carbon atoms), and halogen
atom, hydroxyl group, and phenylthio group.
[0219] X.sup.- represents a non-nucleophilic anion, and includes
those identical with the non-nucleophilic anion as X.sup.- in the
general formula (ZI).
[0220] Preferred compound as the acid generator further includes
compounds represented by the following general formulae (ZIV),
(ZV), and (ZVI).
##STR00035##
[0221] In the general formula (ZIV), two Ar.sub.3 each
independently represents an aryl group.
[0222] R.sub.208 in the general formulae (ZV) and (ZVI) each
independently represents an alkyl group, cycloalkyl group or aryl
group, in the same manner as the alkyl group, cycloalkyl group, or
aryl group as R.sub.204 to R.sub.207 in the general formulae (ZI)
to (ZIII).
[0223] A represents an alkylene group, alkenylene group, or arylene
group.
[0224] More preferred compounds among the acid generators include
compounds represented by the general formulae (ZI) to (ZIII).
[0225] Examples of the acid generators are described below, but the
invention is not limited thereto.
##STR00036## ##STR00037## ##STR00038## ##STR00039## ##STR00040##
##STR00041##
[0226] The acid generators can be used each alone or as a
combination of two or more of them.
[0227] The content of the acid generator in the positive type
resist composition for liquid immersion exposure is preferably from
0.1 to 20 mass %, more preferably, from 0.5 to 10 mass %, further
preferably, from 1 to 7 mass % based on the total solid content of
the resist composition.
(C) Alkali Soluble Compound Having Alkyl Group of 5 or More Carbon
Atoms.
[0228] The positive type resist composition for use in liquid
immersion exposure according to the invention contains an alkali
soluble compound (C) having an alkyl group of 5 or more carbon
atoms.
[0229] Heretofore, when a resist with no problem in usual exposure
is subjected to liquid immersion exposure, development defects
occurred frequently. However, since penetration of water during
liquid immersion exposure can be suppressed by the addition of the
alkali soluble compound (C) having an alkyl group of 5 or more
carbon atoms, development defects and scums can be decreased.
Further, when the alkali soluble compound (C) is added to a resist
with large leaching amount to the liquid immersion solution, the
effect of suppressing leaching can be obtained.
[0230] The alkali soluble compound (C) is a compound which is
alkali-soluble, that is, a compound soluble to an alkali developer
(ordinarily, an aqueous alkaline solution having a pH of from 10.0
to 15.0 at 23.degree. C.).
[0231] Therefore, the alkali-soluble compound (C) has an alkali
soluble group and/or a group which is solubilized by hydrolyzation
with an alkali developer.
[0232] The alkali soluble group includes, for example, a phenolic
hydroxyl group, carboxylic acid group, fluorinated alcohol group,
sulfonic acid group, sulfone amide group, (sulfonyl) (carbonyl)
methylene group and active methylene group. Specific examples of
the active methylene group include
--C(.dbd.O)--CH.sub.2--C(.dbd.O)--, --C(.dbd.O)--CHR--C(.dbd.O)--
(where R represents an alkyl group),
(--C(.dbd.O)--CH(C(.dbd.O)).sub.2--,
--SO.sub.2--CH.sub.2--C(.dbd.O)--), etc.
[0233] Preferred alkali-soluble group includes, for example,
carboxylic acid group, fluorinated alcohol group (preferably,
hexafluoroisopropanol), sulfonic acid group and sulfone amide
group.
[0234] The group which is solubilized by hydrolyzation with an
alkali developer includes, for example, a lactone group, ester
group, sulfoneamide group, and acid anhydride, the lactone group,
sulfoneamide group, and acid anhydride being preferred.
[0235] The amount of the alkali soluble group (acid group) is,
preferably, from 2 to 10 mmeq/g and, more preferably, from 2 to 8
mmeq/g as an acid value of the alkali soluble compound (C). The
acid value is based on the measurement of the amount of potassium
hydroxide (mg) necessary for neutralizing the compound.
[0236] The alkali soluble compound (C) has an alkyl group of 5 or
more carbon atoms.
[0237] The alkyl group of 5 or more carbon atoms is preferably
linear or branched, and has preferably 6 or more carbon atoms, more
preferably, 8 or more carbon atoms. The upper limit for the number
of carbon atoms is preferably 100 or less, further preferably, 50
or less.
[0238] The alkyl group of 5 or more carbon atoms is preferably a
fluorine-substituted alkyl group, particularly, a perfluoroalkyl
group (for example, perfluorooctyl group or perfluorobutyl
group).
[0239] The number of fluorine atoms present in the
fluorine-substituted alkyl group is preferably from 5 to 100, more
preferably, from 9 to 50.
[0240] The alkali-soluble compound (C) has alkyl groups of 5 or
more carbon atoms in an amount, preferably, from 5 to 95 mass %,
more preferably, from 10 to 80 mass % based on the molecular weight
of the alkali soluble compound (C).
[0241] The alkali soluble compound may be either a low molecular
compound or a high molecular compound (for example, a resin). The
molecular weight is preferably, from 300 to 200,000, more
preferably, from 500 to 200,000, further preferably, from 500 to
100,000.
[0242] In a case where the alkali soluble compound is a resin,
those described below are preferred.
(a) The amount of residual monomers is, preferably, 0 to 10 mass %,
further preferably, 0 to 5 mass %. (b) The molecular weight
distribution (Mw/Mn: also referred to as degree of dispersion) is
usually within a range from 1 to 5, and those ranging, preferably,
from 1 to 4, and further preferably from 1 to 3 are used. From the
view point of resolution, resist configuration, side walls of
resist patterns, and roughness, the molecular weight distribution
is preferably 5 or less.
[0243] The addition amount of the alkali soluble compound (C) in
the positive type resist composition for liquid immersion exposure
is preferably from 1 to 60 mass %, more preferably from 1 to 40
mass %, most preferably from 1 to 10 mass % on the basis of the
total solid content of the resist composition.
[0244] In a case where the positive type resist composition for
liquid immersion exposure is a resist composition for ArF exposure,
it is preferred that the alkali soluble compound contains no
aromatic ring.
[0245] The alkali soluble compounds may be used each alone or a
plurality of them may be mixed.
[0246] In a case where the alkali soluble compound is a resin, is
can be synthesized by ordinary methods (for example, radical
polymerization as in the synthesis of the acid decomposable resin
(A) described above).
[0247] The alkali soluble compound (C) is preferably a resin
comprising at least one repeating unit represented by the following
general formulae (Ca) to (Cf).
##STR00042##
[0248] In the general formulae (Ca) to (Cf), Xc's each
independently represents a hydrogen atom, a methyl group or an
alkyl group having 5 or more carbon atoms.
[0249] Rc.sub.1's each independently represents a hydrogen atom, or
an alkyl group having 5 or more carbon atoms.
[0250] Rc.sub.2's each independently represents an alkyl group
having 5 or more carbon atoms.
[0251] Rf.sub.1 and Rf.sub.2 each independently represents a
hydrogen atom or an alkyl group. At least one of Rf.sub.1 and
Rf.sub.2 represents a fluorine-substituted alkyl group.
[0252] Q represents a single bond or a divalent linking group.
[0253] Qc represents a single bond or a (nc+1)-valent linking
group.
[0254] nc represents a positive integer, preferably represents a
integer of from 1 to 5, and more preferably represents a integer of
1 or 2.
[0255] The linking group preferably includes, although not
particularly restricted, a single bond, alkylene group,
cycroalkylene group, ether group, thioether group, carbonyl group,
ester group, amide group, sulfoneamide group, urethane group and
urea group, alone or in combination of two or more of them. Among
them, alkylene group, cycroalkylene group and ester group alone or
in combination of two or more of them are specifically
preferred.
[0256] Specific examples of the high molecular weight alkali
soluble compound (resin) are described below, but they are not
restricted to them.
##STR00043## ##STR00044## ##STR00045## ##STR00046## ##STR00047##
##STR00048## ##STR00049## ##STR00050## ##STR00051## ##STR00052##
##STR00053## ##STR00054## ##STR00055## ##STR00056##
[0257] A polymer containing a perfluoroalkyl group at the terminal
end of the polymer can be synthesized by using a chain transfer
agent substituted at the terminal end with the perfluoroalkyl
group.
[0258] Examples of the low molecular weight alkali-soluble compound
(C) are described below, but they are not restricted to the
examples.
##STR00057## ##STR00058## ##STR00059##
(D) Organic Solvent
[0259] The positive type resist composition for liquid immersion
exposure according to the invention is used while being dissolved
in a predetermined organic solvent.
[0260] The organic solvent which can be used includes, for example,
ethylene dichloride, cyclohexanone, cyclopentanone, 2-heptanone,
.gamma.-butyrolactone, methylethyl ketone, ethylene glycol
monomethyl ether, ethylene glycol monoethyl ether, 2-methoxyethyl
acetate, ethylene glycol monoethyl ether acetate, propylene glycol
monomethyl ether, propylene glycol monomethyl ether acetate,
toluene, ethyl acetate, methyl lactate, ethyl lactate, methyl
methoxypropionate, ethyl ethoxypropionate, methyl pyruvate, ethyl
pyruvate, propyl pyruvate, N,N-dimethyl formamide, dimethyl
sulfoxide, N-methyl pyrrolidone, methoxy butanol, and
tetrahydrofuran.
[0261] In the invention, a mixed solvent prepared by mixing a
solvent having a hydroxyl group and a solvent having no hydroxyl
group in the structure may be used as the organic solvent.
[0262] The solvent having a hydroxyl group includes, for example,
ethylene glycol, ethylene glycol monomethyl ether, ethylene glycol
monoethyl ether, propylene glycol, propylene glycol monomethyl
ether, propylene glycol monoethyl ether and ethyl lactate. Among
which propylene glycol monomethyl ether and ethyl lactate are
preferred.
[0263] The solvent having no hydroxyl group includes, for example,
propylene glycol monomethyl ether acetate, ethylethoxy propionate,
2-heptanone, .gamma.-butyrolactone, cyclohexanone, butyl acetate,
N-methyl pyrrolidone, N,N-dimethyl acetoamide and dimethyl
sulfoxide, among which propylene glycol monomethyl ether acetate,
ethyl ethoxy propionate, 2-heptanone, .gamma.-butyrolactone,
cyclohexanone, and butyl acetate are preferred, and propylene
glycol monomethyl ether acetate, ethylethoxy propionate and
2-heptanone are more preferred.
[0264] The mixing ratio (mass) of the solvent having a hydroxyl
group and the solvent having no hydroxyl group is preferably, from
1/99 to 99/1, more preferably, from 10/90 to 90/10, further
preferably, from 20/80 to 60/40. A mixed solvent containing 50 mass
% or more of the solvent having no hydroxyl group is particularly
preferred in view of the uniformity upon coating.
[0265] By using such a solvent, a resist composition at a solid
concentration usually from 3 to 25 mass %, preferably, from 5 to 22
mass %, more preferably, from 7 to 20 mass %, further preferably,
from 5 to 15 mass % is prepared.
(E) Organic Basic Compound
[0266] The composition of the invention, with an aim of preventing
aging fluctuation of the performance after the irradiation of the
actinic ray or the radiation to the heat treatment (T-tope shape
formation of the pattern, sensitivity fluctuation, fluctuation of
pattern line width, etc.), aging fluctuation of performance after
coating and, further, excessive diffusion of acid (degradation of
resolution) after irradiation of the actinic ray or the radiation
and during heat treatment, an organic basic compound can be used.
The organic basic compound is, for example, an organic basic
compound containing a basic nitrogen, and those compounds with a
pKa value of a conjugated acid of 4 or more are used
preferably.
[0267] Specifically, the following formulae (A) to (E) can be
mentioned.
##STR00060##
[0268] where R.sup.250, R.sup.251 and R.sup.252 may be identical
with or different from each other, and each represents an alkyl
group of 1 to 20 carbon atoms, cycloalkyl group of 1 to 20 carbon
atoms, or aryl group of from 6 to 20 carbon atoms, in which
R.sup.251 and R.sup.252 may join to each other to form a ring. A
substituent which may be present in each of the groups includes an
amino group and hydroxyl group.
[0269] R.sup.253, R.sup.254, R.sup.255 and R.sup.256 may be
identical with or different from each other, and each represents an
alkyl group of 1 to 6 carbon atoms.
[0270] Preferred examples include, for example, guanidine,
aminopyridine, aminoalkylpyridine, aminopyrrolidine, indazole,
imidazole, pyrazole, pyrazine, pyrimidine, purine, imidazoline,
pyrazoline, piperazine, aminomorpholine, and aminoalkyl morpholine.
Those compounds may have a substituent, and preferred substituent
includes, for example, an amino group, aminoalkyl group, alkylamino
group, aminoaryl group, arylamino group, alkyl group, alkoxy group,
acyl group, acyloxy group, aryl group, aryloxy group, nitro group,
hydroxyl group, and cyano group.
[0271] Particularly preferred compounds include, for example,
guanidine, 1,1-dimethyl guanidine, 1,1,3,3-tetramethyl guanidine,
imidazole, 2-methylimidazole, 4-methyl imidazole, N-methyl
imidazole, 2-phenylimidazole, 4,5-diphenyl imidazole,
2,4,5-triphenyl imidazole, 2-aminopyridine, 3-aminopyridine,
4-aminopyridine, 2-dimemthylamino pyridine, 4-dimethylamino
pyridine, 2-diethyl aminopyridine, 2-(aminomethyl)pyridine,
2-amino-3-methyl pyridine, 2-amino-4-methyl pyridine,
2-amino-5-methyl pyridine, 2-amino-6-methyl pyridine, 3-aminoethyl
pyridine, and 4-aminoethyl pyridine.
[0272] 3-aminopyrolidine, piperazine, N-(2-aminoethyl) peperazine,
N-(2-aminoethyl)pyperidine, 4-amino-2,2,6,6-tetramethyl piperidine,
4-piperidino piperidine, 2-iminopiperidine,
1-(2-aminoethyl)pyrrolidine, pyrazole, 3-amino-5-methyl pyrazole,
5-amino-3-methyl-1-p-tolylpyrazole, pyrazine,
2-(aminomethyl)-5-methyl pyrazine, pyrimidine,
2,4-diaminopyrimidine, 4,6-dihydroxypyrimidine, 2-pirazoline,
3-pirazoline, N-aminomorpholine, and N-(2-aminoethyl)morpholine,
but, they are not restricted to them.
[0273] In addition, basic ammonium salts can be used. Specific
examples of the basic ammonium salts can include those compounds
described below, but they are not restricted to them.
[0274] Specifically, they include ammonium hydroxide, ammonium
triflate, ammonium pentaflate, ammonium heptaflate, ammonium
nonaflate, ammonium undecaflate, ammonium tridecaflate, ammonium
pentadecaflate, ammonium methyl carboxylate, ammonium ethyl
carboxylate, ammonium propyl carboxylate, ammonium butyl
carboxylate, ammonium heptyl carboxylate, ammonium hexyl
carboxylate, ammonium octyl carboxylate, ammonium nonyl
carboxylate, ammonium decylcarboxylate, ammonium
undecylcarboxylate, ammonium dodecadecyl carboxylate, ammonium
tridecyl carboxylate, ammonium tetradecyl carboxylate, ammonium
pentadecyl carboxylate, ammonium hexadecyl carboxylate, ammonium
heptadecyl carboxylate, and ammonium octadecyl carboxylate.
[0275] The ammonium hydroxide described above includes
specifically, tetramethyl ammonium hydroxide, tetraethyl ammonium
hydroxide, tetrapropyl ammonium hydroxide, tetrabutyl ammonium
hydroxide, tetrapentyl ammonium hydroxide, tetrahexyl ammonium
hydroxide, tetraheptyl ammonium hydroxide, methyl trioctyl ammonium
hydroxide, tetraoctyl ammonium hydroxide, didecyldimethyl ammonium
hydroxide, tetrakisdecyl ammonium hydroxide, dodecyl trimethyl
ammonium hydroxide, dodecylethyl dimethyl ammonium hydroxide,
didodecyl dimethyl ammonium hydroxide, tridodecylmethyl ammonium
hydroxide, myristylmethyl ammonium hydroxide, dimethylditeradecyl
ammonium hydroxide, hexadecyl trimethyl ammonium hydroxide,
octadecyl trimethyl ammonium hydroxide, dimethyl dioctadecyl
ammonium hydroxide, tetraoctadecyl ammonium hydroxide,
diallyldimethyl ammonium hydroxide, (2-chloroethyl)-trimethyl
ammonium hydroxide, (2-bromoethyl)trimethyl ammonium hydroxide,
(3-bromopropyl)-trimethyl ammonium hydroxide,
(3-bromopropyl)triethyl ammonium hydroxide, glycidyl trimethyl
ammonium hydroxide, choline hydroxide,
(R)-(+)-(3-chloro-2-hydroxypropyl)trimethyl ammonium hydroxide,
(S)-(-)-(3-chloro-2-hydroxypropyl)-trimethyl ammonium hydroxide,
(3-chloro-2-hydroxypropy)-trimethyl ammonium hydroxide,
(2-aminoethyl)-trimethyl ammonium hydroxide, hexamethonium
hydroxide, decamethonium hydroxide, 1-azoniaproperane hydroxide,
petronium hydroxide, 2-chloro-1,3-dimethyl-2-imidazolinium
hydroxide, and 3-ethyl-2-methyl-2-thiazolinium hydroxide.
[0276] The organic basic compounds can be used by one or more and
more preferably, by two or more of them.
[0277] The amount of the organic basic compound to be used is
usually, from 0.001 to 10 mass %, preferably, from 0.01 to 5 mass %
on the basis of the solid content of the positive type resist
composition for liquid immersion exposure.
[0278] The ratio between the acid generator and the organic basic
compound to be used in the composition, that is, acid
generator/organic basic compound (molar ratio) is, preferably, from
2.5 to 300. Namely, the molar ratio is preferably 2.5 or more in
view of the sensitivity and the resolution, and is preferably 300
or less in view of suppression of degradation of the resolution due
to the thickening with the of the resist pattern up to the heating
treatment after exposure. The acid generator/organic basic compound
(molar ratio) is, more preferably, from 5.0 to 200, further
preferably, from 7.0 to 150.
(F) A Dissolution Inhibitive Compound which is Decomposed Under the
Effect of Acid and Increases the Solubility in an Alkali
Developer
[0279] The positive type resist composition for use in liquid
immersion exposure according to the invention can contain a
solution inhibitive compound that is decomposed under the effect of
an acid and increases the solubility in the alkali developer
(hereinafter also referred to as a "solution inhibitive
compound").
[0280] As the solution inhibitive compound, cycloaliphatic
compounds or aliphatic compounds containing acid decomposable
groups such as cholic acid derivatives containing acid decomposable
groups as described in the proceeding of SPIE, 2724, 355 (1996) are
preferred in order not to lower the transmittance at 220 nm or
less. The acid decomposable group and the cycloaliphatic structure
include those identical as described for the acid decomposable
resin (A).
[0281] The molecular weight of the solution inhibitive compound is,
preferably, 3,000 or less, more preferably, from 300 to 3,000 and,
further preferably, from 500 to 2,500.
[0282] The addition amount of the dissolution inhibitive compound
is, preferably, from 1 to 30 mass %, more preferably, from 2 to 20
mass % based on the entire solid content of the positive type
resist composition for liquid immersion exposure.
[0283] Specific examples of the dissolution inhibitive compound is
to be described below, but it is not restricted to them.
##STR00061##
(G) Surfactant
[0284] The positive type resist composition for liquid immersion
exposure according to the invention can further contain a
surfactant (G). The surfactant includes preferably, a
fluorine-based and/or a silicon-based surfactant (a fluorine-based
surfactant, a silicon-based surfactant, or a surfactant having both
a fluorine atom and a silicon atom), or two or more of them.
[0285] Since the resist composition for liquid immersion exposure
according to the invention contains the surfactant (G), it has
enhancing effect on the sensitivity, resolution, adhesiveness,
suppression of development failure, etc. upon use of exposure light
source at 250 nm or less, particularly, 220 nm or less.
[0286] The fluorine-based and/or silicon-based surfactants, can
include surfactants disclosed in, for example, JP-A Nos. 62-36663,
61-226746, 61-226745, 62-170950, 63-34540, 7-230165, 8-62834,
9-54432, 9-5988, Japanese Patent Application No. 2002-277862, U.S.
Pat. Nos. 5,405,720, 5,360,692, 5,529,881, 5,296,330, 5,436,098,
5,576,143, 5,294,511, and 5,824,451, and commercially available
surfactants described below can also be used as they are.
[0287] Commercially available surfactants include, for example,
fluorine-based or silicone-based surfactants such as F-top EF301,
and EF303 (manufactured by Shin-Akita Kasei K.K.), Florad FC430,
431 and 4430 (manufactured by Sumitomo 3M, Inc.), Megafac F171,
F173, F176, F189, F113, F110, F117, F120 and R08 (manufactured by
Dainippon Ink and Chemicals, Inc.), Surflon S-382, SC101, 102, 103,
104, 105, and 106, (manufactured by Asahi Glass Co., Ltd.), Troysol
S-366 (manufactured by Troy Chemical Industries, Inc.), F-top
EF121, EF122A, EF122B, RF122C, EF125M, EF135M, EF351, 352, EF801,
EF802, EF 601 (manufactured by JEMCO Inc.), PF636, PF656, PF6320,
PF6520 (manufactured by OMNOVA SOLUTIONS, INC.), FTX-204D, 2080,
2180, 230G, 204D, 208D, 212D, 218, 222D (manufactured by NEOS) etc.
Further, a polysiloxane polymer KP-341 (manufactured by Shin-Etsu
Chemical Co., Ltd.) can also be used as the silicon-based
surfactant.
[0288] In addition to the known surfactants described above,
surfactants using polymers having a fluoro aliphatic group derived
from a fluoro aliphatic compound produced by a telomerization
method (also referred to as a telomer method) or an oligomerization
method (also referred to as oligomer method) can also be used. The
fluoro aliphatic compound can be synthesized by a method described
in JP-A No. 2002-90991.
[0289] As the polymer having a fluoro aliphatic group, copolymers
of monomers having a fluoro aliphatic group and a
(poly(oxyalkylene))acrylate and/or (poly(oxyalkylene)) methacrylate
are preferred, and they may be distributed at random or
block-copolymerized. The poly(oxyalkylene) group includes
poly(oxyethylene) group, poly(oxypropylene) group,
poly(oxybutylene) group, etc, and, in addition, may be a unit
having alkylenes of different chain length in the same chain, for
example, poly(block-connected form of oxyethylene and oxypropylene
and oxyethylene) and poly(block connection form of oxyethylene and
oxypropylene), etc. Further, the copolymer of the monomers having a
fluoro aliphatic group and (poly(oxyalkylene))acrylate(or
methacrylate) includes not only binary copolymers but also ternary
or higher copolymers formed by simultaneously copolymerizing
monomers having two or more different fluoro aliphatic groups and
two or more different (poly(oxyalkylene))acrylates (or
methacrylates).
[0290] For example, the commercially available surfactants include
Megafac F178, F-470, F-473, F-475, F-476, and F-472 (manufactured
by Dainippon Ink and Chemicals, Inc.). In addition, they include
copolymers of acrylate (or methacrylate) having a C.sub.6F.sub.13
group and (poly(oxyalkylene)) acrylate (or methacrylate), and
copolymers of acrylate (or methacrylate) having a C.sub.3F.sub.7
group, (poly(oxyethylene)) acrylate (or methacrylate) and
(poly(oxypropylene)) acrylate (or methacrylate), etc.
[0291] In the invention, surfactants other than the fluorine-based
and/or silicon-based surfactants can also be used. Specifically,
they include nonionic surfactants, for example, polyoxyethylene
alkyl ethers such as polyoxyethylene lauryl ether, polyoxyethylene
stearyl ether, polyoxyethylene cetyl ether, and polyoxyethylene
oleyl ether, polyoxyethylene alkyl allyl ethers such as
polyoxyethylene octyl phenol ether and polyoxyethylene nonyl phenol
ethers, sorbitan fatty acid esters such as
polyoxyethylene.polyoxypropylene block copolymers, sorbitan
monolaurate, sorbitan monopalmitate, sorbitan monostearate,
sorbitan monooleate, sorbitan trioleate, and sorbitan tristearate,
and polyoxyethylene sorbitan fatty acid esters such as
polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan
monopalmitate, polyoxyethylene sorbitan monostearate,
polyoxyethylene sorbitan trioleate, and polyoxyethylene sorbitan
tristearate.
[0292] In the invention, surfactants represented by the following
general formula (W) may also be used.
##STR00062##
In the general formula (W),
[0293] R.sub.w represents a hydrogen atom or an alkyl group,
[0294] m represents an integer of 1 to 30,
[0295] n represents 0 or an integer of 1 to 3, and
[0296] p represents 0 or an integer of 1 to 5.
[0297] The alkyl group in R.sub.w is preferably a linear or
branched alkyl group of 1 to 5 carbon atoms and includes, for
example, a methyl group, ethyl group, propyl group, n-butyl group,
sec-butyl group, and t-butyl group. Among them, methyl group, ethyl
group and propyl group are preferred.
[0298] In the general formula (W), it is preferred that m
represents an integer of 1 to 25, n is an integer of 0 to 2, and p
is an integer of 0 to 3.
[0299] Preferred examples of the surfactant represented by the
general formula (W) include, for example, commercially available PF
636 (n=0, m=6, p=1, and R.sub.1=methyl group in the general formula
(W)), PF 6320 (n=0, m=20, p=1, and R.sub.1=methyl group), PF656
(n=1, m=6, p=1, and R.sub.1=methyl group in the general formula
(W), and PF 6520 (n=1, m=20, p=1, and R.sub.1=methyl group in the
general formula (W)), (all manufactured by OMNOVA SOLUTIONS,
INC.).
[0300] The surfactants may be used each alone, or may be used as a
combination of several of them.
[0301] The amount of surfactant (G) to be used is preferably, from
0.01 to 5 mass %, more preferably, from 0.1 to 3 mass % based on
the entire amount of the resist composition for liquid immersion
exposure (except for solvent).
(H) Alkali Soluble Resin
[0302] The positive type resist composition for liquid immersion
exposure according to the invention can further be incorporated
with a resin which is soluble to an alkali developer, whereby the
sensitivity is improved.
[0303] In the invention, novolac resins having a molecular weight
of 1,000 to 20,000 or polyhydroxystyrene derivatives having a
molecular weight of about from 3,000 to 50,000 can be used as such
a resin. However, since they have large absorption relative to the
light of 250 nm or less, it is preferred that they are used while
being partially hydrogenated, or used in an amount of 30 mass % or
less based on the entire amount of the resin.
[0304] In addition, resins having a carboxyl group as an alkali
soluble group may also be used. The resin having the carboxyl group
preferably has a mono-nuclear or poly-nuclear cycloaliphatic
hydrocarbon group for improving the dry etching resistance.
Specifically, they include a copolymer of a methacrylic acid ester
having a cycloaliphatic hydrocarbon structure showing no acid
decomposability and a (meth)acrylic acid or a resin of
(meth)acrylic acid ester of a cycloaliphatic hydrocarbon group
having a carboxyl group at the terminal.
[0305] The addition amount of such alkali soluble resin is usually
30 mass % or less based on the total amount of the resin including
the acid decomposable resin (A).
(I) Carboxylic Acid Onium Salt
[0306] The positive type resist composition for liquid immersion
exposure according to the invention may be incorporated with a
carboxylic acid onium salt.
[0307] The carboxylic acid onium salts in the invention includes
carboxylic acid sulfonium salt, carboxylic acid iodonium salts,
carboxylic acid ammonium salts, etc. Particularly, as the
carboxylic acid onium salts, iodonium salts and sulfonium salts are
preferred. Further, it is preferred that the carboxylate residue in
the carboxylic acid onium salt contains no aromatic group or
carbon-carbon double bond. Especially preferred anion moiety
includes linear, branched, mononuclear or polynuclear alkyl
carboxylic acid anions having 1 to 30 carbon atoms. Further anions
of carboxylic acid in which the alkyl groups are partially or
entirely substituted with fluorine are more preferred. The alkyl
chain may be incorporated with oxygen atoms. This can ensure the
transparency relative to the light of 220 nm or less, improve the
sensitivity and resolution, and improve the density dependence and
exposure margin.
[0308] The anions of fluoro-substituted carboxylic acid include
anions of fluoroacetic acid, nonafluoropentanoic acid,
perfluorododecanoic acid, perfluorotridecanoic acid, difluoroacetic
acid, trifluoroacetic acid, pentafluoropropionic acid,
heptafluorobutyric acid, perfluorocyclohexane carboxylic acid,
2,2-bistrifluoromethyl propionic acid, etc.
[0309] Those carboxylic acid onium salts can be synthesized by
reacting sulfonium hydroxide, iodonium hydroxide, ammonium
hydroxide, on carboxylic acid with a silver oxide in an appropriate
solvent.
[0310] The content of the carboxylic acid onium salt in the
composition is appropriately from 0.1 to 20 mass %, preferably,
from 0.5 to 10 mass %, further preferably, from 1 to 7 mass % based
on the total solid content of the positive type resist composition
for liquid immersion exposure.
(J) Other Additives
[0311] The positive resist composition for liquid immersion
exposure can further be incorporated optionally with dyes,
plasticizers, photosensitizers and compounds for accelerating the
solubility to liquid developer (for examples, phenol compounds
having a molecular weight of 1,000 or less, cycloaliphatic or
aliphatic compounds having a carboxylic group), etc.
[0312] Such phenol compounds having a molecular weight of 1,000 or
less can easily be synthesized by those skilled in the art with
reference to the method described in JP-A Nos. 4-122938, and
2-28531, and U.S. Pat. No. 4,916,210, and EP No. 219,294.
[0313] Specific examples of the cycloaliphatic or aliphatic
compounds having a carboxylic group include carboxylic acid
derivatives having a steroid structure such as cholic acid,
deoxycholic acid, and lithocholic acid, adamantane carboxylic acid
derivatives, adamantane dicarboxylic acid, cyclohexane carboxylic
acid and cyclohexane dicarboxylic acid, but they are not restricted
to them.
[0314] The metal content in the positive type resist composition
for liquid immersion exposure of the invention is preferably 100
ppb or less.
(K) Pattern Forming Method
[0315] The positive type resist composition for liquid immersion
exposure according to the invention is used by dissolving the
ingredients described above in a predetermined organic solvent,
preferably, the mixed solvent described above, and then coating it
on a predetermined support as described below.
[0316] Namely, the positive type resist composition for liquid
immersion exposure is coated at a predetermined thickness (usually,
from 50 to 500 nm) on a substrate (for example, silicone/silicon
dioxide coating) which is used for the manufacture of precise
integrated circuit elements by an appropriate coating method such
as by a spinner or a coater.
[0317] After coating, the resist is dried by spinning or baking to
form a resist film, then subjected to exposure by way of a liquid
immersion solution (liquid immersion exposure) through a mask, etc.
for forming a pattern. The exposure amount can be appropriately
determined and it is usually from 1 to 100 mJ/cm.sup.2. After the
exposure, spinning and/or baking is preferably conducted,
development and rinsing are carried out to obtain a pattern.
Preferably, baking is conducted after the exposure, and the
temperature for the baking is usually from 30 to 300.degree. C.
With a view point of PED described above, it is preferred that the
period of time from the exposure to the baking step is shorter.
[0318] The light for the exposure is far ultraviolet rays at a
wavelength preferably of 250 nm or less, more preferably, 220 nm or
less. Specifically, they include KrF excimer laser (248 nm), ArF
excimer laser (193 nm) F.sub.2 excimer laser (157 nm) and X rays,
etc.
[0319] Incidentally, the change in performance of the resist when
being subjected to the liquid immersion exposure is thought to be
due to the contact between the surface of the resist and the liquid
immersion solution.
[0320] The liquid immersion solution used upon liquid immersion
exposure is to be described below.
[0321] The liquid immersion solution is preferably a liquid which
is transparent to the exposure wavelength and having a temperature
coefficient of the refractive index as small as possible such that
the strength of the optical images projected on the resist is
minimized. Particularly, in a case where the exposure light source
is an ArF excimer laser (wavelength: 193 nm), use of water is
preferred in view of easy availability and easy handling in
addition to the view points described above.
[0322] For the purpose of further improvement of refraction index,
medium having refraction index of 1.5 or more may be used.
[0323] In a case of using water as the liquid immersion solution,
an additive (liquid) that does not dissolve the resist layer on the
wafer and the effect of which to the optical coating at the lower
surface of the lens device is negligible may be added at a slight
ratio in order to decrease the surface tension of water and
increase the surface activity. The additive is preferably an
aliphatic alcohol having the refractive index substantially equal
with that of water and, specifically, it includes, for example,
methyl alcohol, ethyl alcohol, isopropyl alcohol, etc. The addition
of the alcohol of the refractive index substantially equal with
that of water can provide a merit capable of decreasing the change
of the refractive index as less as possible as the entire liquid
even when the alcohol ingredient in water is evaporated to change
the concentration of the content. On the other hand, in a case
where a substance not transparent to a light at 193 nm or
impurities having a refractive index greatly different from that of
water should be mixed, since this causes distortion in the optical
images projected over the resist, distilled water is preferred as
water to be used. Further, purified water filtered by passing
through an ion exchange filter or the like may also be used.
[0324] The electric resistance of water is preferably 18.3
M.OMEGA.cm or more and the TOC (organic material concentration) is
preferably 20 ppb or less. Further, deaeration is applied
preferably.
[0325] The lithography performance can be improved by elevating the
refraction index of the liquid immersion solution. In view of this,
additive for elevating the refraction index can be added in water,
or heavy water (D.sub.2O) may be used instead of water.
[0326] A film less soluble to the liquid immersion solution may
also be disposed between the resist film formed of the positive
type resist for use in the liquid immersion exposure and the liquid
immersion solution of the invention (hereinafter referred to as
"top coat"), in order to avoid direct contact of the resist film
with the liquid immersion solution. The function necessary for the
top coating is the coating adaptability to the portion to the upper
layer portion of the resist, transparency to radioactive rays,
particularly, at 193 nm, and less solubility to the liquid
immersion solution. It is preferred the top coat is immiscible with
the resist and, further, can be coated uniformly to the upper layer
of the resist.
[0327] A polymer not containing the aromatic ingredient is
preferred for the top coat in view of the transparency at 193 nm
and includes, for example, a hydrocarbon polymer acrylate ester
polymer, polymethacrylic acid, polyacrylic acid, polyvinyl ether,
silicon-containing polymer, and fluorine-containing polymer.
[0328] When the top coat is peeled, a liquid developer may be used
or a peeling agent may be used separately. As the peeling agent, a
solvent with less penetration to the resist is preferred. It is
preferred that the resist can be peeled by the alkali developer in
that the peeling step can be applied simultaneously with the
developing step for the resist. With a view point of peeling by the
alkali developer, the top coat is preferably acidic and with a view
point of non-intermixing property with the resist, it may be either
neutral or alkaline.
[0329] The resolution is improved in a case where there is no
difference of the refractive index between the top coating and the
liquid immersion solution. In a case of using an ArF excimer layer
(wavelength: 193 nm) as the exposure light source, since the use of
water as the liquid immersion solution is preferred, it is
preferred that the refractive index of the top coating for use in
ArF liquid immersion exposure is similar with that of water (1.44).
Further, with a view point of transparency and refractive index, a
thin film is more preferred.
[0330] In the case of using organic solvent as the liquid immersion
solution, the top coating is preferably water-soluble.
[0331] As the alkali developer to be used in the developing step,
there can be used, for example, inorganic alkalis such as sodium
hydroxide, potassium hydroxide, sodium carbonate, sodium silicate,
sodium metasilicate, and aqueous ammonia, primary amines such as
ethylamine and n-propylamine, secondary amines such as diethylamine
and di-n-butyl amine, tertiary amines such as triethylamine and
methyldiethyl amine, alcohol amines such as dimethyl ethanolamine
and triethanolamine, quaternary ammonium salts such as tetramethyl
ammonium hydroxide and tetraethyl ammonium hydroxide, and aqueous
alkaline solution such as pyrrol and piperidine.
[0332] Further, the aqueous alkaline solutions may also be used
with addition of an appropriate amount of alcohol or
surfactant.
[0333] As a rinsing solution, purified water is used and it may
also be used with addition of an appropriate amount of
surfactant.
[0334] The alkali concentration of the alkali developer is usually
from 0.1 to 20 mass %.
[0335] The pH of the alkali developer is usually from 10.0 to
15.0.
[0336] After the developing treatment or the rinsing treatment, a
treatment of removing the developer or the rinsing solution
deposited on the pattern can be conducted with a supercritical
fluid.
Example
[0337] The invention is to be described more specifically by way of
examples, but the content of the invention is not restricted to
them.
Synthesis of Resin (1)
[0338] 2-adamantyl-2-propylmethacrylate, 3,5-dihydroxy-1-adamantyl
methacrylate and norbornane lactone acrylate at a molar ratio of
40/20/40 (molar ratio) and dissolved in propylene glycol monomethyl
ether acetate/propylene glycol monomethyl ether=40/40 (mass ratio)
to prepare 450 g of a solution with 22% solid concentration. To the
solution, 1 mol % of a polymerization initiator, V-601 (dimethyl
2,2'-azobis(2-methylpropionate) available from WAKO JUNYAKU KOGYO
CO. was added, which was added dropwise under a nitrogen atmosphere
to 50 g of a mixed solution of propylene glycol monomethyl ether
acetate/propylene glycol monomethyl ether=60/40 (mass ratio) heated
to 100.degree. C. over 6 hours. After the completion of addition,
the reaction solution was stirred for 2 hours. After the completion
of the reaction, the reaction solution was cooled to a room
temperature, a white powder crystallized and deposited on 5 L of a
mixed medium of hexane/ethyl acetate=9/1 (mass ratio) was obtained
through filtration to recover the aimed resin (1). By .sup.13CNMR
and polymer acid value measurement, the polymer compositional ratio
(2-adamantyl-2-propylmethacrylate/3,5-dihydroxy-1-adamantyl
methacrylate/norbornane lactone acrylate (a/b/c) was determined as
39/21/40 (molar ratio). As a result of GPC measurement, the weight
average molecular weight (Mw) on the basis of standard polystyrene
was 9700, and the degree of dispersion (Mw/Mn) was 2.01.
[0339] The resins (2) to (20) which were used in the invention were
synthesized in the same manner as the method for the resin (1).
[0340] The structures of the resins (1) to (20) are described
below.
##STR00063## ##STR00064## ##STR00065## ##STR00066## ##STR00067##
##STR00068## ##STR00069##
Examples 1 to 27 and Comparative Examples 1 to 4
Preparation of Resist
[0341] Ingredients shown in the Table 1 were dissolved each in
solvent to prepare solutions at 10 mass % concentration for solid
content, and filtered through a 0.1 .mu.m polyethylene filter to
prepare positive type resist compositions for use in liquid
immersion exposure. Each of the positive type resist compositions
for use in the liquid immersion exposure thus prepared was
evaluated by the following method and the results are shown in
Table 1. When the ingredients are used in plurality, the ratio
between them is expressed by mass ratio.
[0342] An organic antireflection film ARC 29A (manufactured by
Nissan Chemical Co.) was coated over a silicon wafer, and baked at
205.degree. C. for 60 sec to form an anti-reflection film at 78 nm.
A positive type resist composition for use in liquid immersion
exposure thus prepared was coated, and baked at 120.degree. C. for
60 sec to form a resist film of 150 nm. The thus obtained wafer was
put to 2-beam interference exposure by a device shown in FIG. 1
using pure water as the liquid immersion solution (wet exposure).
The wavelength of the laser used was 193 nm, and a prism forming a
90 nm line & space pattern was used. Just after exposure, it
was heated at 125.degree. C. for 90 sec and then developed with an
aqueous solution of tetramethyl ammonium hydroxide (2.38 mass %)
for 60 sec, rinsed with pure water and then spin-dried to obtain a
resist pattern.
[0343] In the apparatus shown in FIG. 1, are shown a laser 1, a
diaphragm 2, a shutter 3, reflection mirrors 4, 5, and 6, a
condensing lens 7, a prism 8, a liquid immersion solution 9, a
wafer 10 provided with an anti-reflection film and a resist film,
and a water stage 11.
<Evaluation Method>
[Development Defect]
[0344] Number of development defects was measured for the resist
pattern obtained as described above by using KLA-2360 apparatus
manufactured by KLA Tencor Japan and the obtained primary data
values were used as the result of measurement.
[Scum]
[0345] The remaining state of development residues in a resist
pattern of 90 mm line width obtained as described above (scums) was
observed by a scanning type electron microscope (S-9260,
manufactured by Hitachi) and evaluated as A for those not observed
with residues, as C for those observed with considerable residues
and as B for those therebetween.
[Leaching Amount of Generated Acid]
[0346] The prepared resist composition was coated on a 8 inch
silicon wafer, and baked at 115.degree. C. for 60 sec to form a
resist film of 150 nm. After exposing the resist film by an
exposure apparatus at a wavelength of 193 nm for the entire surface
at 50 mJ/cm.sup.2 and then 5 ml of pure water deionized by using a
super pure water manufacturing apparatus (Milli-QJr, manufactured
by NIPPON MILLIPORE) was dropped on the resist film. After placing
water, on the resist film for 50 sec, the water was sampled, and
the concentration of the acid leached therein was determined by
LC-MS. [0347] LC apparatus: 2695, manufactured by Water Co. [0348]
MS apparatus: Esquire 3000 plus manufactured by Bruke Kaltonics.
Co.
[0349] The concentration of the leached anion species of the
photoacid generator (PAG) was measured by the LC-MS apparatus.
TABLE-US-00001 TABLE 1 Composition Evaluation Resin Photo acid
Solvent Surfactant Dissolution inhib- Alkali soluble Number of
Leaching (2 g) generator (mg) (mass ratio) (5 mg) itive compound
(g) compound (C) defects Scum degree (%) Example 1 1 z2(20)
SL-4/SL-6 W-1 -- .sup. (E-1) 300 A 5 (60/40) 2 2 z2(24) SL-2/SL-4
W-2 -- (D-1) 310 A 6 (50/50) 3 3 z6(28) SL-1/SL-4/SL-8 W-3 -- .sup.
(E-4) 320 A 7 (40/58/2) 4 4 z1(20) SL-2/SL-4 W-4 -- .sup. (E-2) 310
A 6 (40/60) 5 5 z2(20) SL-2/SL-4 -- -- (D-2) 300 A 5 (40/60) 6 6
z6(20) SL-2/SL-4/SL-9 W-4 -- (E-1)/(D-2) 330 A 7 (40/59/1) (10/90)
7 7 z6(20) SL-2/SL-4 W-1 -- (D-1)/(E-7) 310 A 8 z9(15) (50/50)
(50/50) 8 8 z38(20) SL-2/SL-6 W-1 -- (D-4) 360 B 12 (70/30) 9 9
z2(30) SL-2/SL-4/SL-9 W-1 -- .sup. (E-1) 310 A 6 (40/59/1) 10 10
z2(25) SL-2/SL-4 W-2 -- (D-1)/(D-5) 300 B 8 (40/60) (70/30) 11 11
z38(12) SL-2/SL-4 W-3 -- (E-1)/(E-7) 330 A 7 z2(25) (40/60) (90/10)
12 12 z6(12) SL-2/SL-4 W-4 -- (D-1)/(D-3) 270 A 2 z31(10) (40/60)
(70/30) 13 13 z6(22) SL-1/SL-7 W-4 I-1 (D-3) 280 A 3 z25(10)
(40/60) (0.1) 14 14 z2(32) SL-4/SL-6 W-1 -- .sup. (E-22) 320 A 7
(60/40) 15 15 x38(40) SL-3/SL-7 W-3 -- (D-1)/(D-2) 310 A 8 (60/40)
(70/30) 16 16 z3(33) SL-2/SL-5 W-2 -- (D-1)/(E-7) 310 A 6 (60/40)
(20/80) 17 17 z2(50) SL-2/SL-7 W-2 I-2 (D-4) 350 B 13 (60/40) (0.1)
18 18 z38(27) SL-2/SL-7 W-1 -- (D-3) 280 A 2 (60/40) 19 19 z6(29)
SL-2/SL-7 W-1 -- (D-1)/(D-2) 310 A 6 (60/40) (80/20) 20 20 z3(25)
SL-2/SL-4 W-4 -- (D-3) 300 A 5 (40/60) 21 1 z55(100) SL-2/SL-4 W-1
-- (D-6) 270 A 8 (40/60) 22 2 z55(80) SL-2/SL-4 W-1 -- (D-7) 310 A
5 (30/70) 23 1 z56(20) SL-4/SL-6 W-2 -- (D-8) 300 A 8 z14(10)
(60/40) 24 1 z34(120) SL-2/SL-4 W-2 -- (D-9) 280 A 6 (30/70) 25 2
z60(5) SL-2/SL-4 W-1 -- (D-9) 280 A 6 z67(40) (40/60) 26 2 z67(40)
SL-2/SL-4 W-1 -- (D-9) 280 A 8 (40/60) 27 1 z55(30) SL-4/SL-6 W-4
-- (D-10) 300 A 8 z60(10) (60/40) Comparative 1 1 z2(24) SL-4/SL-6
W-1 -- -- 650 C 30 Example (60/40) 2 2 z2(24) SL-2/SL-4 W-1 -- --
670 C 32 (60/40) 3 3 z2(24) SL-4/SL-6 W-1 -- -- 620 C 35 (60/40) 4
4 z2(24) SL-4/SL-6 W-l -- -- 650 C 33 (60/40)
[0350] The symbols in Table 1 are as follows.
[0351] Acid generators correspond to those exemplified above.
[0352] SL-1: cyclopentanone [0353] SL-2: cyclohexanone [0354] SL-3:
2-methylcyclohexanone [0355] SL-4: propylene glycol monomethyl
ether acetate [0356] SL-5: ethyl lactate [0357] SL-6: propylene
glycol monomethyl ether [0358] SL-7: 2-heptanone [0359] SL-8:
.gamma.-butyrolactone [0360] SL-9: propylene carbonate [0361] W-1:
Megafac F176, (manufactured by Dainippon Ink and Chemicals, Inc.)
(Fluoro type) [0362] W-2: Megafac R08, (manufactured by Dainippon
Ink and Chemicals, Inc.) (Fluoro and silicon type) [0363] W-3:
Polysiloxane polymer KP-341 (manufactured by Shin-Etsu Chemical
Co., Ltd.) (Silicon type) [0364] W-4: Troysol S-366 (manufactured
by Troy Chemical Industries, Inc.). [0365] I-1: t-butyl
lithocholate [0366] I-2: t-butyl adamantane carboxylate
[Low Molecular Alkali Soluble Compound]
[0366] [0367] E-1: A compound having an alkali soluble group
exemplified above, with an acid value of 2.6 mm equivalent/g.
[0368] E-2: A compound having an alkali soluble group exemplified
above, with an acid value of 2.4 mm equivalent/g. [0369] E-4: A
compound having an alkali soluble group exemplified above, with an
acid value of 5.0 mm equivalent/g. [0370] E-7: A compound having an
alkali soluble group exemplified above, with an acid value of 3.6
mm equivalent/g. [0371] E-22: A compound having an alkali soluble
group exemplified above formed by hydrolysis by the alkali
developer exemplified above, with an acid value of 0.0 mm
equivalent/g.
[High Molecular Alkali Soluble Compound]
[0371] [0372] (D-1) to (D-10): High molecular alkali soluble
compounds shown in Table 2 (resins).
[0373] The repetitive unit constitutions (C-1), (C-7), (C-19),
(C-23) and (C-31) to (C-33) in Table 2 mean repetitive unit
constitutions of the alkali soluble compounds exemplified above
(resins). The compositional ratios are molar ratios of the
repetitive units. The unit of the acid value is mm
equivalent/g.
TABLE-US-00002 Alkali soluble Constitution of Compositional
Molecular Dispersion Acid compound repetitive units ratio weight
degree value (D-1) (C-1) 50/50 10000 1.4 3.9 (D-2) (C-1) 70/30
15000 1.4 6.3 (D-3) (C-7) 50/50 8000 1.3 1.6 (D-4) (C-19) 50/50
8000 1.4 2.4 (D-5) (C-23) 50/50 8000 1.3 2.8 (D-6) (C-31) 80/20
12000 2.1 4.4 (D-7) (C-31) 60/40 5000 1.8 3.1 (D-8) (C-32) 70/30
12000 1.5 2.0 (D-9) (C-33) 80/20 7000 1.7 2.0 (D-10) (C-33) 60/40
7000 1.8 1.6
[0374] The results of Table 1 show that, upon liquid immersion
exposure, the positive type resist composition for liquid immersion
exposure according to the invention has small number of development
defects and scum, and that the leaching thereof to the liquid
immersion solution is suppressed.
[0375] The present invention can provide a positive type resist
composition suitable to liquid immersion exposure suppressing
development defects, scums and leaching of the resist ingredient to
the liquid immersion solution during liquid immersion exposure, as
well as a method of forming a pattern using the same.
[0376] The entire disclosure of each and every foreign patent
application from which the benefit of foreign priority has been
claimed in the present application is incorporated herein by
reference, as if fully set forth.
* * * * *